Smyth Busters: Should You Bed an AR-15 Barrel?

Brownells Gun Techs™ Caleb Savant and Steve Ostrem are back to put another firearm myth to bed, one way or another. Today's myth is that you can improve your AR-15's accuracy by bedding the barrel into the upper receiver. "You mean gluing it in place?" queries Steve. Actually, yes. The barrel extension usually fits into the receiver with a slightly snug slip fit. Proponents of "bedding" an AR-15 barrel use green Loctite® 294 to anchor the barrel extension in the receiver. These folks think bedding the barrel prevents it from wobbling, thus making their AR-15s more accurate.
This might help secure a particularly loose-fitting barrel extension. But under normal circumstances, a properly tightened barrel nut locks the barrel firmly in place. When the barrel nut is torqued down, the shoulder of the barrel extension is pressed tightly to the front of the receiver. Also, tightening the nut actually compresses the receiver around the barrel extension, almost like a collet. Some AR-15 manufacturers even make their upper receivers slightly undersized to obtain this extra-tight compression fit. BOTTOM LINE: Wobble or flexing of the barrel in the upper is normally not an issue.
If the barrel extension fits so poorly that after you tighten the barrel nut, it's still shimmying around like a dancer in a 1980s MTV music video, your upper is probably seriously out of spec. Rather than reaching for the green Loctite®, the better solution is to get a new, in-spec upper receiver.
If you do decide to bed your AR-15's the barrel, you might as well lap the receiver to get the straightest, cleanest possible metal-to metal fit. Brownells offers an Upper Receiver Lapping Tool for this purpose. But with most high-quality uppers, lapping is not necessary. (Ssshhhh! Don't tell the Marketing Dept. Caleb said that.)
So the myth that you should bed your AR-15 barrel is BUSTED. Bedding may have been necessary years ago when manufacturing tolerances on receivers and barrel extensions were looser. If you think you need to bed a barrel, you probably have other problems and should look into just getting a different upper receiver and/or barrel extension.

[@CalebSavant]

If you have a buddy that's wasting green locktite on the reg, go ahead and smash that like and subscribe button.

[@printingwithpeek4897]

What's up man@

[@US2A]

Lol

[@josh48315]

This ain’t busted. Bedding has been proven to make a difference. Criterion does this, they recommend it, and they make some of the most accurate barrels. Really Caleb is going to doubt the folks at Criterion? You don’t NEED to do it, but if you want to take a 1 MOA gun to 0.5 or 0.75 MOA then yes bed your barrel with Loctite 620. It also keeps your groups tighter for longer as groups open up with more firing. And it’s STUPID EASY to do, there’s no extra steps, you just put some green loctite on instead of grease and install like normal. There’s no reason not to do it. And all BCM uppers are thermal fit even their stripped uppers, it literally comes with a piece of paper in the box that says this. Criterion recommends a thermal fit upper and green loctite. See their videos AR15 Science and Accurizing the AR15.

[@WilliamAM43]

So where is “That’s all we got for you. Just one more thing, Steve you got some dad advice for us” 🤣 Garand Thumb reference

[@TheCrewChief374]

Wait? Are you saying that bedding doesn't have anything to do with sleeping with your AR in bed with you? 😁 Of course, I wonder what all that green stuff was that my AR was leaving all over my bed😁

[@n.u.t.y.]

I think the shimming and bedding of AR-15s comes from the work that Joe Carlos did when he was armorer for the Army precision shooting team. He believed that when the barrel heats up, any gap could allow shifting, causing consistency issues in precision matches. He wrote this up in American Gunsmith magazine. Personally, I have seen fairly loose fits, even with top-name parts, so I'd think that shimming and bedding is a good idea. I've also seen top-name uppers that were 5 thou out of square, so I'd also thinking lapping may be a good idea. Either that, or get really good at sending stuff back.

[@blizzcustoms2632]

Had this issue with a rock river arms rifle. After bedding and lapping the barrel, there was a noticeable improvement in accuracy. I wouldn't care to do it on any rifle that I wasn't trying for accuracy with though.

[@blizzcustoms2632]

@@LRRPFco52 I found one of the videos you are talking about, it's called building match grade ar15s by a channel called "funshootvideo".

[@Josh-dx4tu]

I was about to comment with that same article. I have always lapped and bedded my AR uppers. It certainly hasn't hurt anything, even if the bedding part is unnecessary.

[@YumekuiWRX]

Very much this. A tolerance stack of a top name brand barrel on the minus side and a top name brand receiver on the plus side does not indicate crappy parts. And if you have a clone receiver (A1, A2, C7...) you don't just "get a new one" because you probably already had to bare knuckle box someone for the chance to buy it. I've never seen much use in any bedding compound, but I've taken to shimming my barrels to fit just tightly enough that you can't pull them apart with a firm tug. Shim stock is cheap enough and is easily reversible. Knock the barrel out with a firm tap on a dowel and you've undone the "mod" when the shim stock falls out.

[@jaydunbar7538]

The issue with the idea of the barrel heating up and causing movement is the barrel grows with heat, it gets a tighter fit not looser. Experts are experts in their field, not in anything else. Being a good trigger man does not make you a good builder, nor does being a good builder make a good trigger man. Sure their will always be a some overlap do to the tasks being related, a F1 mechanic is also probably a good driver that doesn’t make them ready to drive the next Grand Prix.

[@MrWhipple42]

Should I bed an AR-15 barrel? Maybe if it buys me dinner first…

[@ChristianGrest]

This one hurt. I've done barrel extension bedding- in the past. Arguably it does little if anything but take up slack on a loose fitting receiver/barrel extension. I always true the receiver face though and like you mentioned, most don';t need it. But I like to feel like I'm doing more than just assembling, so I enjoy it. Great video fellas!

[@AC-bl1rl]

I'm with you, I don't believe the barrel nut compresses the fit, I think crooked faces will cock the barrel, making people think it got tighter. Face'em, and add green and/or a shim to get it tight.

[@AC-bl1rl]

@@LRRPFco52 They were also very likely cherry-picking each component from batches for a prime fit. Just about no one else, can do that. They may have even been getting special parts made. Must be nice, haha!

[@LRRPFco52]

@@AC-bl1rl Yup. AMU eventually specified their own receivers with exact call-outs on extension tunnel ID, and BAT machine extensions made across a set of ODs so they could go with more of a press-fit, hand-fit to each upper. Joe Carlos said he still uses Green Loc-tite on those, after years of testing with their fleet rifles chasing accuracy and precision, where bedding continued to show an edge.

[@DinoNucci]

@@LRRPFco52 wrong

[@DinoNucci]

@@AC-bl1rl wrong

[@TacticalConsiderations]

I use lapping to verify the upper was machined flat and usually one side has been high. Those uppers included, aero/Ba, anderson, sun devil, daniel, adm, dpms and many others. The only two I did that were flat was a blackout defense and cobalt.

[@Zel_eo]

[Story Time] I regularly build uppers for friends and relatives since I have all the tools, gauges, and grease needed. A while back I had a friend ask me if I would build an upper for a buddy of his. I said sure and he gave me all the parts about a week later. Everything was name brand on the build (Geissele, DD, SA, etc.) so it all fight perfectly with a dab of grease. This guy comes to pick it up the next day and the first question he asks me is "Did you bed my barrel?". I told him no because until this point I had only ever heard of bedding a bolt rifle. I informed him that everything was properly greased and torqued to spec. He told me I didn't know what I was doing because grease would allow the barrel to slip around in the receiver. Needless to say but I have not built for him again.

[@royrogers3624]

"You guy why does this regularly and has good results know nothing while I who have never done it and have no tools or experience and an expert" Those are the only people who actually bother me

[@Zel_eo]

@@royrogers3624 Hit that nail right on the head. That attitude is so strange to me. While I might question someone's method, If they can show me how and why it works, I will 100% add it to my book of knowledge.

[@lincolnpascual]

Fudds will fudd bro. I charge extra for folks like that. It's a stupid relic that doesn't even apply to ARs, or the majority of modern firearms anyway.

[@jjsingh3379]

Tell him if he wants a bedded barrel, get a JP thermo fit upper.

[@thefunstuff6121]

The guy is clearly an expert because he has watched some KZbin videos. Physics don't matter when you're a professor of KZbinology

[@jimlaxton8004]

I have personally experimented with it. I found that even with parts from highly reputable manufacturers, I could tighten up my groups by up to 1/4 MOA by bedding the barrel. Many people may not care about this amount of improvement on an AR15 style rifle. If tightening your group is important to you, it can make a difference. I tried it on a few rifles, where they were shooting slightly over 1 MOA, and after bedding they were a little under 1 MOA. Although we may want absolute answers that are always right, the true answer is usually "It Depends".

[@docholliday3273]

First I have heard about this. If you have a loose fit that bad, then you need to stop right there and don't go any further because there is another issue.

[@unclebob540i3]

Good point! If the fit is that loose, break out the gauges and micrometers, something is out of spec.

[@tonystreetman8209]

Probably an Anderson upper lol

[@suhy9861]

Mine is an Anderson 5.56 barrel (16in, 1:8, $100) and an Aero Precision slick upper (the cheap $90 one), the fit between the barrel and reciever is SUPER tight that i couldnt do it by hand, i carefully smacked it into place with a rubber mallet and I'm on my way to the range right now to give her a test of accuracy and see if a cheap Amderson barrel can hold up to M193 55gr (normal target ammo i know)

[@PrezVeto]

"If you're gonna bed it, you might as well lap it" Words to live by. Show em a good time.

[@dwp138]

I anti seize my barrel. Thanks for this.

[@gamerjenkins2053]

Sounds like something the ATF needs to look into. "Anti-Seize". Sounds like a good name for an act to abolish them.

[@dw7094]

GMD (GREASE, MOLYBDENUM DISULFIDE, MIL-G- 21164)

[@alexfreund9460]

Can't believe Caleb put it in dry on Valentine's Day!

[@stillededge]

😂

[@bradborton4802]

I use Wilson combat uppers on all my builds and every one has been very tight on all my barrels during install. No lapping needed or shims. All have been 1\2 moa builds. Thanks guys for your I sight on this matter. Please keep it coming!

[@Eric-hx2or]

😂😆

[@country4life534]

Great video thanks and hopefully in the future I'll have to repair less things like this on customer guns.

[@louielindenmayer6653]

I've used green loctite and tried shimming on what felt like a really loose arrangement - then went to BCM upper for a truly tight fit. I think heat transfer from the barrel extension is better, too.

[@DinoNucci]

No

[@2A.Freedom]

The thermal fit that bcm and others do really eliminates any reason people would have for using loctite. Permatex anti seize is the way to go. Same with the buffer tube. I never need to lap the receiver also.

[@wirebrush]

Try this. Find an upper and barrel with a sloppy fit and put it together with a very long free float handguard and measure the deflection between the barrel and the front of the handguard when pressing the barrel to the side, then disassemble and shim the barrel extension and measure the movement again between the barrel and handguard when pressing with the same force. In my experience you will see a difference and if there isn't enough clearance between the gas block and handguard that little bit of extra stiffness can be the difference between the gas block touching the handguard when the barrel moves when fired, or not, which can make a huge difference in accuracy.

[@unclebob540i3]

Great discussion! I have spoken with very reputable rifle manufacturers who swear by it, and equally reputable barrel manufacturers who recommend against it. I bedded my varmint .223 and didn't on another similar build, both shoot sub MOA all day. My sample size of one each did not make a difference, so I don't bother.

[@fowllab]

Good information. Thanks

[@EmpTy-kf2rq]

Lap it, bed it and that will rule out those items if there is an accuracy issue. Instead of having to take everything apart again to do it. Best effort from the start. I have both seen and not seen accuracy improvements by lapping and bedding. The barrel whips/vibrates significantly and can cause the barrel to shift within the upper receiver.

[@HBomb157]

I tried lapping and bedding on my last build. The accuracy was disappointing at first (not a cheap upper Giselle super duty). After lapping and bedding, I want to say it improved,but its hard to tell. Definitely didn't hurt.

[@crazy4milsurps]

Yeah done it to a handful of builds and that the best result I have had "it didnt hurt" lol can not say it wasted time however since working on guns is a form of thereapy for me.

[@richardmartinek3467]

I have done it with my first build. I didn't like the group. After lapping and the same torque it made an improvement about 3/8" it was an Aero upper I now do it on all of my builds. I guess there could have been other factors unknown to me. So I lap away and my AR 10 will shoot 3/4" with hunting rounds (308). My .02

[@johnq.public5911]

When I read your "TITLE", I BUSTED OUT LAUGHING!!! As you state; IF your parts are THAT loose, you better trash that piece and get a good quality part!

[@airborneivan]

I bed my barrels if the barrel extension fitment into the upper is loose. I have experienced accuracy improvements, BUT I'd say that the average casual shooter most likely won't notice it. I personally prefer a thermal fit. Either an undersized upper or a slightly oversized barrel extension.

[@DinoNucci]

Wrong.

[@ThePatriotParadox]

I know that after building my first couple that I really come to appreciate BCM and their thermo fit uppers and handguards along with a steel barrel nut in-between and steel hardware, so super tight fitment and after all put together when that aluminum does heat up, it's pressing against steel barrel nut/rail hardware to make the fit of everything even tighter and more secure. Definitely NOT a bad way to engineer a complete upper!

[@CatRacer1a2a]

Every upper build I do starts with a BCM reciever. I absolutely love them.

[@ThePatriotParadox]

@@CatRacer1a2a can't go wrong with anything BCM

[@litoaykiu]

Aluminum expands twice as fast as steel; that thermo fit goes right out the window!

[@leyderness3553]

Never used green loctite to lock a barrel in but I do shim the barrel for a tight fit. I have found that, that has helped accuracy.

[@kevinhood1224]

Caleb has the coolest sideburns in the gun game and I say that in all jealousy! Lol. Love the videos guys. Always great info and entertainment

[@NCHiker1970]

I own the Lapping tool and have used it on all of my AR upper receivers but have never bedded the barrel using locktite because a local gunsmith told me it was a waste of time.

[@DinoNucci]

Correct

[@claytondennis8034]

I've lapped all my builds, and I agree with Caleb. Of all those builds, only 1 receiver needed it, and it was a cheap upper to start with.

[@Jack-xy2pz]

I enjoy Smythbusters.. Keep it going.

[@Andrew-jm4tp]

I felt bad about not lapping or bedding, but then my rifle shot MOA at 100 yards and I realized I didn't miss out on much.

[@DinoNucci]

Correct

[@dickjohnson7845]

YES!! If you have a tight fight when installing the barrel to the receiver and I mean tight to the point you have to either heat the receiver or freeze the barrel, then there is no bloody reason to bed or shim the barrel extension.

[@boss350z5]

BCM does that with their uppers. I have built several off of blem uppers and in each case heat was required...

[@OTG414]

Lapping the upper receiver does make a pretty big difference IMO. I have seen about a 1/2 MOA improvement, on average, in my groups between un-lapped vs lapped receivers. I actually break my new barrels in on an un-lapped receiver, then tear the gun down and lap the receiver before reassembling the gun. I never ever “bed” my barrel extensions though. In fact, I always use a light application of anti-seize on my barrel extensions and receiver threads to prevent galling. I really recommend a “break-in and tear-down” when I build rifles for people. You really need that time and stress on the threads and mating surfaces. They will stretch and move as the parts “settle in” to each other. I see much better accuracy and reliability when I follow this procedure.

[@PBVader]

That's a good tip. Wish today's females were taught that removing stress and reevaluating makes the next round of stress manageable. Now onto the lack of passive cathodic protection between two dissimilar metals as compared to high speed galling two similar metals that cannot maintain oil film.

[@frankmorris8150]

I also build, shoot, then take it apart. But... I bed the barrel and lapp the receiver. I have noticed my groupings shrink almost in half. I don't know which process caused it. But what the heck. If it works, it works. Ill probably get bored and try both methods out to see if I see any difference now.

[@fender19281]

this seems wild to me that this is a thing. the barrel is literally clamped down to the upper w a nut with the proper torque, it's not going anywhere. Esp from medium strength Loctite that basically turns to dust when heated to a certain temperature.

[@DinoNucci]

CORRECT

[@1boortzfan]

Sounds like a great explanation.

[@MrWilk_Firearms]

I had a ding from the factory on the front of my Wilson Combat forged upper once. The lapping tool helped remove that ding and true up the receiver. I have pics if Brownells marketing wants them 😂

[@clloydhi]

I use the Wheeler facing tool to square off the face of the receiver before I install the barrel. The guns I have done this too have all been fairly accurate...I use a quality barrel at the get go so this step helps I'm sure.

[@H.R.6688]

The last build I did, I just lapped the reciever face, because I had to use a rubber mallet to get the barrel in place.

[@Citizensoldier85-ik6er]

I like the thermal fit uppers, a lot of persicion shooters are over sizing the barrel extension and turning it down to fit the upper

[@fmxmyway]

I had D. Wilson bed, shim, and lathe my receiver and it is the most accurate AR I’ve ever shot. I don’t think it hurts.

[@DinoNucci]

Wrong

[@fmxmyway]

@@DinoNucci How old are you? 12?

[@DinoNucci]

@@fmxmyway Thank you for asking. I am indeed old enough to: A) Build my own AR's B) Understand the basics of mechanics Tootles Ma'am.

[@fmxmyway]

@@DinoNucci Build your own junk AR*

[@bdove7939]

That is good one. Maybe it will work to keep loose under wear up too. Let me try that.

[@chocolatemonk]

I hadn't seen this one, thx

[@97n2oGT]

I usually just lap it with a 600 grit media real quick. If it’s an even pattern I’ll clean it and start the build. Always do it on a vertical plan too.

[@koffeekage]

My Armalite upper was sloppy. I put compound on the receiver extension and let it dry, then fitted it into the receiver. I also had to lap the face of the receiver so i figured why not do both.

[@maxcole3930]

I wrap my barrel extension with a piece of wheat break then jam it into my uppers. Can't be white bread, gotta be wheat...I use green lock tight on my PB & j sandwiches. PB & lock tight yummm!!!

[@AN-nt2bz]

Bedding the barrel definitely helps. If you are shooting for precision, I recommend it. The only reason you need to shim, is if the gap between the extension and barrel exceeds .001, which is easy to test. Just put the .001 shim material in between the extension and the receiver, if you can pull it out, it will benefit from the shim. otherwise, use the bedding material and move on. If you are shoot for practical accuracy, shimming and bedding the barrel is a waste of time. An AR15 will shoot 1.5 to 2 MOA with M855/M193 ammo as designed.

[@SSAe2]

Criterion recommends it, although not sure about the lock tight method.

[@CalebSavant]

Because they want to make sure you dont blame their barrel for that $30 dollar Bear Creek special quality fitment upper receiver.

[@US2A]

@@CalebSavant don't hate

[@sauceboss3101]

@@CalebSavant based

[@benjaminbrown1179]

Most important thing with the matting of the upper receiver, and the barrel is to make sure the face of the upper is cut square to the centerline of the upper. Also the threads are cut square. Most of the time it's not needed

[@actionjksn]

I use moly grease on mine. The two I did with expensive receivers from VLTOR with good $300+ barrels were so tight I had to put a piece of 2x4 on the end of the barrel and knock it in with a hammer. I didn't have to blast it real hard or anything but it was nice and snug and I was pretty happy about that. Even using grease, there was no way you were just pushing those things together. When me and Caleb go to remove our barrels I will bet we have a better experience than the guys who used loctite. Spend the money on a good quality upper receiver. It holds the barrel and the bolt carrier group. You want a good fit with your barrel and you want everything milled where it is very concentric and straight, and no sloppy fit with the barrel. You can also tell the difference when you work the action because it feels and sounds very smooth, compared to a cheap upper receiver.

[@floridagunrat1625]

Mostly, I use my lapping tool to verify that the face of the AR receiver has been machined true. As someone that shot competitively and was reasonably successful and also spent many years building competition rifles, you just don't want any potential for movement, misalignment, expansion/contraction issues under temperature shifts, xcetera. So we take no chances. We try and be as precise as possible and we try and keep everything as tight as possible. That being said most of these procedures are lost on the average Hunter/plinker/sporting rifle.

[@americanmilitiaman88]

All the AR 15s i have assembled barrels fit nice and tight. I recently did a aero M5 build with criterion barrel. Slight movement used grease as i normally would torqued it to spec used the shims that aero called for and no more movement or concerns

[@evanacey1414]

Zev/Mega Arms receiver sets require you to thermo-fit your barrel as well, and they are an OEM for SOLGW, GGP, and a few other AR-15 “manufacturers” out there.

[@Vecto_Vindictus]

I've gotten into the habit of using stainless shims and a lapping tool, I used green LT once and it seems to really not do much but squirt out and make a mess. unless it's a BCM upper which I've gravitated to using more often. I've seen a tiny improvement on a couple of rifles, like 1/4" group reduction at 100 yards. I did however see a really great improvement on a PSA upper, but that could have been a torque thing. In any case, it doesn't really hurt anything so why not?

[@calicojack556]

I have a 6.5 Grendel AR. It shot ok at first - just ok. I tore it apart, lapped the receiver and and bedded the barrel. I notice a huge difference in accuracy. Now you might say the barrel just needed to be broken in; who knows? I agree that the bedding is probably not required, and it makes replacing a barrel a PITA. Lapping I think can only help.

[@KidCorporate]

I've "bedded" a barrel when I felt like the fit between the upper and extension wasn't where I wanted it, but usually I build with stuff where the tolerances require thermofitting which at that point there's no reason to do anything else, once the upper cools down it's not going anywhere.

[@smptactical259]

My Zev Core Elite upper receiver also needed heat to fit the barrel. I’ve lapped my upper receivers but I have not bedded them, I think glue is is not necessary. No issue with the machining, its the layering of paint on the upper receiver which may not be consistent. Just more peace of mind than proven and tested improvement. I will say I’m not disappointed with the accuracy, but that my just be me on a good day with extremely favorable conditions.

[@brudamiranda3314]

Good morning gentlemen!!

[@christopheravery5808]

I was never taught to bed the upper receiver and to only lap it if the barrel doesn’t fit flush to the receiver

[@robertdinicola9225]

I only ever found 1 anderson that was not square and needed lapping. It was less than .001 out. I got the tool just for checking the uppers with feeler guages.

[@l800x8]

I bought a Charles Daley AR-15, must've been around year 2000 before they went out of business, and I couldn't get that sucker to shoot. Eventually I figured out that there was zero torque on the barrel nut. Totally loose. I lapped it, cemented it in with 600F gasket material and torqued it. Shot fine after that. Been retired to house duty for a decade, since I dread changing barrels on it. As far as dimpling on barrels, or pinning for the gas blocks, I don't know about that either. I have changed some barrels, and the loctite on the gas blocks screws had seeped between the gas block and the barrel and I spent a good twenty minutes pounding the gas blocks off.

[@jcnikoley]

I’ve only bedded one AR-15. It had a poor fit between the extension and receiver. It also required shimming. Accuracy was improved, but could be attributed as much to final torque. All others I’ve only used molybdenum grease.

[@tjkiller99000]

Ive seen extension shims improve a barrels accuracy more than once. Have used loctite but a sloppy fit needs corrected.

[@ES44AC-2]

I use Aeroshell greese on mine and a properly torqued barrel nut. Never had an issue.

[@DinoNucci]

Correct

[@sluttybutt]

Re: lapping: the issue isn't with forging vs machining. It's the fact that the anodize process takes a perfectly squared surface and then alters it in a non-uniform manner. Correct lapping is done when the receiver extension is about 3/4 bare aluminum with a little ano left on the lowest points, in order to counteract the irregularities caused by anodize. I've never had a single receiver from any "quality" manufacturer come out exactly square until lapped out of the seven or so I've done so far.

[@theunofficialresults231]

This

[@theunofficialresults231]

Everything from BCM to Palmetto. Once I lapped a BCM and saw the correction it made, I took apart every one I owned and lapped them. I do not remember one being square. Does it help? Don't know, but can't hurt.

[@sluttybutt]

@@theunofficialresults231 it can if you chuck it up in a drill like many do, and overdo it by taking it down to the point where the whole end face is bare, but yeah, generally it's not a bad thing

[@joschmo6020]

New comment/Point Thank you Caleb & Co. This was a great piece. The Good Idea “Fairy” is definitely alive & well in the online firearms community. Sometimes to our detriments. It can go from comical to potentially dangerous real quick when someone shares their thoughts, theories & ideas. Some are good, but in my opinion any type of internal critical components of a gun should never be “tinkered” with without having the proper training. Here is one good example, and this one (idea) has actually made all the way up to where major players in the firearm accessory market are being produced. My example is the Glock pistol. Right now you can buy plugs for the well that resides directly behind the magazine well at the bottom of the pistols grip. Some plugs come with a Glock pin take down tool also and seem pretty ingenious. What the rub is that if you read your manuals you will learn that this (for lack of better terms) ‘chimney’ is there to allow debris from the trigger mechanism to be ejected safely from the gun. I imagine if you plug that up then debris could pile up and eventually alter the designed functionality of the firearm. Unless you take a recognized armorer’s course, let’s leave the gun design to the engineers? You know, the ones with degrees in design, lol. I believe that ingenuity is what makes Americans special, but we must be cautious. You don’t need a 2lb competition trigger in a home defense pistol. The adrenaline will likely end up discharging the firearm unintentionally. Stay safe and have fun! Bryan K. KORE-4 Firearm Safety Institute

[@JenkinsStevenD]

Get a bravo company USA blemished upper. They are $60 or so on sale. Freeze the barrel, heat up the upper threads, insert...once that barrel and receiver hit ambient temp again, that isn't coming out anyway. You can't pull it out without tools. Most of their "blem" uppers don't even have blemishes. I never bed them and haven't had an issue yet. Premium upper on a budget with rock solid fitment. I've had uppers that weren't BCM and would wiggle until the barrel nut is on there and it never created an issue. I don't trust the lapping tools but to each their own.

[@jasonshink6589]

I love all these fools that lap😂😂😂😂you're telling me that some Brownells tool for a couple bucks I put in my hand drill or drill dress at best that I square up with my hand tools and levels will be more true than when it cake from the factory??? Lmao. All that material ppl see is you ramming that tool in wobbling around shheering off the inside if your upper. .......BCM is great by the way. What a bitch to put on.

[@CplSkiUSMC]

Lapping and bedding are another level of meticulous and in the pursuit of perfection one does not just call it good enough and hope for the best. The average Joe might think lapping and bedding are over the top but I've seen anywhere from noticeable to drastic improvements in different rifles as a result.

[@richardxstroker]

I’m not a bedder, but I do lap my receivers. I prefer the stainless shim and thermo fit method.

[@CplSkiUSMC]

@@richardxstroker I've heard about the shims but I haven't tried them. I know there are some quality uppers that are specifically made to be thermo fit but I have tried them either. I've had good luck with lapping and Loctite 638 which is the high temp gap filler but I might like to try the shims... I wouldn't have to heat the barrel extension to 400 deg to replace the barrel.

[@richardxstroker]

@@CplSkiUSMC I think JP and BCM thermo fit, but don’t quote me. I haven’t had to remove a barrel yet, but in my mind, shims and heat would be easier than using loctite.

[@CplSkiUSMC]

@@richardxstroker Loctite isn't that bad. I've removed a barrel that was Loctited and had to use the heat gun, but It came out. It's a gap filler and does a nice job, but that's not to say that shims don't do a good job as well. It's the meticulous trial and error of installing shims that would be the down side, just as having to heat the barrel extension to remove a barrel is a down side of Loctite. The important thing is to get that barrel fit to the extension as solid as possible to achieve that degree of accuracy that we all love so much. In the pursuit of that end, I think we're willing to deal with the down sides of whichever method we choose because tight groups will make your day every time.

[@richardxstroker]

@@CplSkiUSMC - Pretty much, just a different way to skin a cat, haha

[@antonw-uw4ov]

We lap a lot of receivers of a bunch of different brands at my firm. They are usually not perfectly square. It is more rule than exception for them to be a little off. Coating the barrel extension in loctite and where necessary using shim-stock has been shown in well designed testing With multiple rifles to increase accuracy by shrinking groups at 100yrd by arond 30% if i remember correctly. A tight fit in the receiver is necessary to not have the barrel shift during heat and vibration since steel and aluminium expand at different rates. To use the example of a collet in a mill; you would not expect good results from putting a 9mm end mill in a 10 collet and just cranking it harder to make up for the poor fit.

[@DinoNucci]

Wrong. Please provide the name of "your firm"

[@egnah2]

I have used Permatex gasket shellac on a receiver and barrel that were already very accurate .25"-.50" groups at 100 yards. (The upper receiver is a Seekins SP223 billet upper which is a very rigid/robust receiver and the barrel is made by Lothar Walther) I separated the two and gave them a through cleaning and reassembled with the shellac. Next day at the range using the 2 loads that shot the best I was able to shoot .25'-.33" groups so a bit of improvement. Was it worth it ? Probably not in reality .... The gun is my designated whistle pig whacker and it is the only time I have tried it . I have built several since and have not had the urge to try it again. On another note I started using BCM uppers which have a thermal fit so they fit the extension extremely tight but they don't seem as rigid as the Seekins. Just my Two Cents. I enjoy your videos !!!!

[@DinoNucci]

Wrong

[@twisted_oddball]

I thought Caleb slept with his AR-15 barrels, I was sorely disappointed by this.

[@alannaofrann6767]

I've seen people tighten the extension with thin shimstock. They swore by it.

[@123nicefellow123]

Shimming takes some effort to get it precise but it is really satisfying when the barrel ends up tight in the upper receiver. An advantage of shimming is that it tells you how good the fit between the extension and the upper receiver is. The larger the shim has to be, the worse it is without. On the other hand, if the shim gets so thin that you cannot mount the barrel without damaging the shim in the process you know the fit is good enough that you don't need the shim. Also I trust a shim much more when the extension heats up versus glue which might turn into a sauce more and more.

[@JH-oh1in]

I prefer a thermal expansion fit. Bedding though I would say is to elevate tolerance stack. If you are piece mealing parts together (especially in the DPMS Ar-10s) the specs are all over the map. Bearing mount (green loctight) is able to absorb a +/- .003 discrepancy. Once cured it can be chemically removed but will not degrade much from heat or vibration. No I would never want to try and take it apart again. In the diesel world its been used to help erosion issues at liner faces injector cup sealing ect.. May not be a best practice but like anything its a way to resolve an issue. making holes smaller isn't always in the cards.

[@kylez3145]

I've bedded with loctite 620 snd removed it. Removing it wasn't as bad as I thought

[@jesseww]

Aw man I did not know you sold a lapping tool. I will have to get one. If anything just to check my parts.

[@michaelsanbornsniper8231]

As a Master Gunsmith I really appreciate your videos! Spot on. No lapping, no bedding on AR’s!

[@christopherascherl2411]

I've had one receiver that definitely needed to be lapped. It was stringing badly and lapping fixed it. I do it every time now since I have the tool and it is so easy to do.

[@ThePatriotParadox]

I agree if your having bad problems with inconsistent accuracy then it may be a thing I would do as a gunsmith, but most the time putting decent part's together correctly I get great accuracy.... But there's always a chance of getting a bad apple

[@bobborlog1677]

So no truing the upper receiver face

[@ThePatriotParadox]

@@bobborlog1677 you can if you want, although with good parts I've gotten 1 MOA most the time, it's not a bad thing.... Just not always necessary..... Especially not glueing in the barrel extension unless a super loose upper/barrel extension interface

[@LRRPFco52]

As a master gunsmith, how would you construct your argument against lapping and bedding if another master gunsmith and AMU armorer told you they tested this on large fleet sizes with their rifles, with tens of thousands of match rounds, and saw that it definitely improved accuracy and precision?

[@baileyparadis1815]

Sample size of one here, but one of my previous Colt builds I did lap and bed the barrel. The upper was very close to true, but I did notice the finish wearing off quicker on one side than the other. I didn't use loctite, but used shim stock and cut a piece to size that gave the barrel extension a tight fit. Did this really give me anything? Not that I'll ever probably notice. But did I satisfy my OCD? Absolutely.

[@noche7864]

4:07 love that you guys collet how you see it

[@longbow6245]

The first rifle I put together was several years ago when parts were really hard to get. This was a high dollar build except for the upper and lower. It has a very sloppy barrel extension to receiver fit. I bedded with blue locktite. I should have shimmed and bedded. This rifle still has a first shot cold bore flier if the barrel is not warm. It shoots decent if you don't count the first shot. I built a Grendel with a VLTOR upper and Lilja barrel that I had to thermally fit together. No cold bore fliers with it. Three shot clover leafs you can cover with a dime.

[@NoWr2Run]

Sounds like you should rebed with GREEN RETAINING COMPOUND ? Maybe even Steel Shim Stock also ?

[@lawrenceoliver6491]

I was replacing the barrel in an AR and for that to be true of My BCM upper that was purchased as a complete upper... Which would have been nice to know, but I figured it out myself and used the heat gun on it.

[@calebdavis3110]

I actually found that BCA or Bear creek arsenal, also requires heating to fit.

[@Sparks52]

Bedding is a waste of Loctite and makes disassembly for barrel replacement (e.g. .556mm to .300 Blackout) a Royal PITA. One should use the proper Umbrella 33MS/64 grease on the barrel extension and barrel nut. I do lap the receiver only going far enough into the finish to verify that it is concentric. Never had one that wasn't, but it also makes the receiver end flatter so that it fully butts up to the barrel extension flange. Never had a barrel fit loosely -- or had one so tight I needed to use a heat gun. The secret to lapping is to do it by hand with the receiver vertical and **NOT** using a drill on the tool, working slowly. This I've done with Ballistic Advantage barrels, Aero Precision uppers, and Aero Precision Atlas R-One MLOK handguards that come with proprietary barrel nuts. Properly torqued nuts with concentric, flat upper end is sufficient. Its accuracy will exceed 99.9999999999% of shooter capability.

[@DinoNucci]

Correct.

[@bensmith9164]

Some of this recently probably came from carrytrainer video at criterion where he talked about thermofit and bedding the barrel to make it a "super tight rigid fitment" when they replaced his barrel.

[@geraldphillips8999]

I have bedded many barrels into upper receivers. I did this after finishing the build and testing accuracy. In my own platforms I have seen huge accuracy gains after bedding the barrel. I utilize a shim and locktite to get the fit I want. Before you say it was the shim that made the difference I have to let you know that I shimmed without bedding and I just bedded the barrel. I saw improvements using the methods separately but when I used them together I saw the most improvement. I do more than just bedding the barrel. I also lap the barrel along with aligning the bcg with the bore. I have several ar platforms that shoot an average of half MOA and will hold that to extended ranges beyond eight hundred yards. I don’t care if you believe me, that’s the process I use. There’s a lot of tolerance issues in the ar platform and taking out as much as I can makes the platform more accurate.

[@DinoNucci]

Wrong.

[@lawerncemiller6557]

Amen brother I made the same statement here and I guess you have read some of the replies, guess if your just shooting steel at 50 yards an doesn't matter where you hit it it's a step in assembling an AR you can skip but if you want a really accurate rifle the fit between the barrel extension and upper receiver should be tight !

[@geraldphillips8999]

@@DinoNucci I'm just stating the results I have acheived.

[@xxshooterxxdm]

I have tested this on many ar rifles and have yet to find a ar upper that was perfect. Put them in the lathe and put your gauge on it you will find out. Tru them up and bed them might not get 1/2 moa but we do see at our shop around 1/4 to 1/3 moa accuracy improvements in most cases with good quality ammo.

[@ScreamingReels4365]

I've had two upper receiver/barrel extensions that were a loose fit. I did not notice accuracy issues, but I did notice consistency issues after I first shot them. I pulled them and used 0.001 shim stock to tighten up the fitment between the extension and the upper. The accuracy remained the same, but the consistency issues disappeared. I now will buy uppers like BCM that are said to have tighter fitment to ensure the best fit possible.

[@engine22emt]

“I’m looking at you “ love it

[@blugrassmaniac]

I’ve done test on sloppy uppers compared to bedding and actually got more accuracy out of bedding. I agree you don’t need it but it can work.

[@jayhitek]

I had to do that once, for a barrel that I couldn't get onto a upper. heated my upper and put my barrel in the freezer for half a day.. Expansion and contraction. I got it on! Probably never coming off.

[@amo757]

I lap and bed. I hunt with my AR (6.5 Grendel), so I want the best accuracy possible. It is so quick and easy to do, why not do it. I still put a light coat of oil on the barrel exrension, but none on the upper, so the bedding compound only bonds to the upper, not the barrel. This makes it easier to remove the barrel. I do agree though that a thermal fit is best.

[@murphymmc]

Good stuff guys, then there is the disassembly that eventually will occur, green Loctite will surely make that seamless 😉and presents another, gotta clean that crap off to reinstall, step . With my bull barrel I get 1/2 MOA with normal dry fit torquing, I ain't messin' with that.

[@daviddrago9360]

I’ll make sure the face on the receiver is flat and concentric to the receiver, but the barrel nut will center the barrel and if there’s that much play than either barrel extension or receiver isn’t of proper dimension. I’ve installed a barrel without lapping process, then removed barrel and lapped the receiver and it did improve accuracy. It’s not the machining that’s the issue, it’s the anodization isn’t always even on those edges and it creates a better surface area for the barrel to rest improving harmonics on the barrel. I’ll even take a small flat file and very lightly flatten the area and you will see the defects (Follow hand guard specs on torque for barrel nut) cranking on a barrel nut is bad and cranking on a muzzle device is worse. So If harmonics wasn’t or isn’t a concern, then neither is accuracy to you. I prefer to be sub MOA and can do it all day with an AR that has a chrome lined chf barrel (with my hand loads of coarse cuz factory ammo sucks and even some of the so called match crap they sell) 😮

[@wildcard556]

I’ve honestly never heard this term before now. Can’t say I like the idea either, just a personal opinion. I mean barrels come and go, depending on shooting schedule, and other reasons or possible deficiencies, so I would rather use barrel grease.

[@jesusisalive3227]

How can you come to a conclusion without testing it?

[@tnnaas]

Bed an AR-15 barrel? Without dinner first? I know it's Valentine's Day, but...

[@chrissewell1608]

Usually I have had to add Aeroshell grease to even get my barrels in the receiver. Some times tapping with a persuader. Even with properly bedding the mount! Then I will add some locking gue to the barrel nut, ONLY!

[@DinoNucci]

Wrong.

[@cowboy2267]

I’ve had to remove up to a 1/16” of material off Aero Uppers with a lapping tool to true them. This seems pretty common

[@jfal104]

Sorry if this was already commented about, but at what temp does green Loctite melt? We are talking about the HOTTEST part of a rifle being fired. I use torches to melt Loctite-treated joints to get them released all the time (even Loctite red 272...the strongest of the thread lockers...much stronger than green). Asking for a friend.

[@joesavoca5959]

I know one thing, if you could wiggle your bolt action precision rifle barrel around in the action before torqing down the nut you wouldn't be happy. The Army marksmanship team noticed lubricant bubbling up between the receiver and barrel extension when they wiggled their barrels and we could assume that their barrels were torqued. I use .001 shim stock between the extension and barrel then lap the receiver unless it's a BCM upper.

[@autumnfragrance6326]

The secret here is that Caleb uses Loctite on his hair.

[@stillededge]

Never thought about "bedding" until I saw this while looking for "lapping" videos. My SUSPICION was "eh, tight is tight, if it doesn't move while shooting - doesn't need either." BUT, my AR ain't shooting as straight as I want it too...sooo...I'm trying to eliminate problems I can't see...neither of these is "expensive" and MIGHT help...soo...gonna give them a whirl. Won't have to worry about again until I change the barrel and hopefully I won't need to do that before I die...sooo...if I remember...I'll update when it works or didn't.

[@rmartuszewski]

What these two fail to know, is during covid and many if not all companies having QC issue because of up tic in production of parts. Plus cheap uppers from bad companies. Yes Lapping and bedding uppers can be a must. Now bedding with loc tight is bad. Use thin shim sets from McMaster carr. Also most uppers aren’t flat on the front of the threads on the uppers, they have an angle step, use a magnifying glass and you can see it.

[@themackguyverchannel7713]

You should torque, loosen and retorque a couple of times to seat everything before your final torque spec.

[@benjaminbrown1179]

I will admit that I use grease on my builds. If the upper is out or the barrel extension is out I just don't use them together.

[@misahayase8854]

new to AR's good to know . . . I guess quality upper (and parts) . . .