A Detailed Look at 1911 Slide to Frame Fit & Tightening

[@JaredAF]

Slide to frame fit is very important for getting a good group out of a ransom rest, not as important when it actually comes to firing from the hand because the ransom rest doesn't look through the sights. If the barrel is properly fit to the slide with a nice tight bushing and lock up in the lugs, the sights will be the same relative to the barrel every time. The gains you can get chasing slide to frame fit is incredibly small compared to a properly fit barrel. The best way I've seen a slide tightened up is with laser welding the frame rails. So much cleaner than TIG. Also if you thought this was sketchy, you should see how Beretta frame rails and the barrel bed are tightened up lol

[@EngineersArmory]

The Kuhnhausen manuals state only 15% maximum of the accuracy equation is slide to frame fit. Your explanation of how the barrel and slide lock up is slaved to the iron sights and more important when shooting without a rest makes a lot of sense! I never really thought of it that way. Yeah I think welding/microwelding and machining would be ideal.

[@cindicunningham-d8d]

Thank you for the wonderful explanation. Being from the Structural engineering industry I love this is loaded with great proven and documented facts. I've always followed Kuhnhausen's instructions when doing a slide to frame fit. He was a great man and genius. We are so fortunate to have his works available. Nicely done.

[@EngineersArmory]

I appreciate the kind words. I'm really standing on the shoulders of giants here with the information I am presenting.

[@sjambok1]

Man this is the good non brain rot part of gun tube. Awesome stuff!

[@MichaelEastman-e8v]

The old time armorer at the MTU (marksmanship training unit) at Ft Campbell made his own barrel links, also used the shop vice to squeeze the slide. He gave me a pot of rubbing compound and told me to work the slide till it went home. We cleaned the slide and frame, put the gun back together and shot sub 2” groups at 25 yards. After 40+ years of shooting I recently put a compensator on the pistol. It works good and has lasted a long time.

[@EngineersArmory]

That's awesome!

[@celmer6]

What recoil spring weight did you go with to get it to cycle with the comp? Mine won't cycle with the comp and the Wilson Combat springs that I have installed. I don't want to cut these springs so I ordered a spring assortment from #9lb - 16lb. They should be delivered in a few days.

[@johncrash13]

I was really looking into it, too. Although my B9r after 1000 rounds so far doesn't even have half the rattles i heard in the video. After a lot of research, I read enough people who came to the same conclusion you did. Save the money and sweat equity and just get a tighter gun off the rip like a BA or Staccato. I also read several time and from personal experience with a buddy who has some very expensive older school 1911 that they all will loosen up to a point and it really wont effect anything besides judt feeling as nice. Although I obviously cant attest to that since im so new to the 1911/2011 game. Great video. I love the whiteboard illustrations. Helps the common man like me a lot!

[@PatternRecognitionMusic]

As always, super cool and extremely informative. I love tinkering with my 1911, but this seems like the sort of thing I don't see myself fooling with. My slide to frame fit is probably not match pistol tight, but maybe a little better than combat pistol loose so I'm happy with it.

[@EngineersArmory]

Yeah this was not a fun task. Wouldn't recommend haha. Squeezing the slide and tightening horizontal clearances if anything is the move.

[@Paul_Whaley]

Another great, informative upload! Fun tidbit; Wilson Combat historically has tossed slides into the vice to do their slide to frame fitting. There's a few old videos on their YT channel of 1990s gunsmithing VHS tapes, and they show it there. It's scary, but it works! I'm not planning on doing anything to tighten up my guns. The old custom Colts are plenty tight, and my two Tisas guns have had other work done to make them shoot truer. Thanks again for the detailed video. Loving this series!

[@EngineersArmory]

Honestly, I was surprised how well the slide squeezing worked. Once I got over the initial pucker factor it was fine. I would totally do that again.

[@Paul_Whaley]

@@EngineersArmory Yeah, breaking a slide would certainly be no fun. I think that the Mac9 project is panning out pretty well so far though.

[@EngineersArmory]

@@Paul_Whaley Thanks! Its done finally haha.

[@MyName-tb9oz]

@@Paul_Whaley, what kind of work have you had done on your Tisas? We've got three of them: One B45 and two B45Rs. The 45Rs seem quite tight for the most part. Not Match Competition tight, but not terribly far off. The B45 slide-to-frame fit might be a _little_ less tight but the trigger seems considerably lighter than the 45Rs, which I like. On the whole, it think they're all more accurate than I am at the moment. I'm working on that, though. I'd still like to know what kinds of things you've done to make them more accurate, if you don't mind saying. I've been thinking about stronger recoil springs for +P but I'm not sure I want the added wear.

[@Paul_Whaley]

@@MyName-tb9oz I've actually got videos here on my channel that show what I've done to my two Tisas guns. Since then, I've done some more work (fitted EGW bushings to both guns, and added an oversized firing pin stop to the Stakeout), but the videos are otherwise current.

[@loginpatrycjusza]

Great video. Not an engineer but I do appreciate the thorough explanation of the process as you go. Just subscribed.

[@edccustom101]

Excellent video. When fixing parts in the vise, use paper instead of tape, which is stiffer than tape, as the tape's glue makes the part slippery.

[@EngineersArmory]

Thats a good idea. i didnt have any problems with the frame moving around once I modified my fixture. The tape stayed put.

[@ivanradi4275]

Excellent video and learning experience! I really enjoyed the entire process, the analyses, and the conclusions, which I found very accurate. It would be worthwhile to know, after some time, the wear behavior of both the frame and the slide. Again, thank you for sharing!

[@Le10White]

Very surprised Toob hasnt removed this as they dont allow us to talk bout this.

[@EngineersArmory]

🤫I think my channel is small enough they dont pay attention. Although I have had one video removed before. Shush. Dont talk about it. I also try to fend it off with ample disclaimers.

[@rickgeorgette9657]

Incredible video, thanks!

[@lemonycactus8687]

Super helpful video! I’ve been considering doing the same job myself on my prodigy and this was extremely helpful guidance for the process and points to note.

[@loupuleff571]

I recently did two frame tightening jobs on my personal guns the first is my kimber I used a power customs slide rail tightening jig. Tightening the horizontal also helps in the vertical it worked great. I just learned the other day that the old timers would heat the slides to 400 degrees before tightening horizontally I did not know about that when I did mine.The other did not work so I ended up buying a new slide and fit it to the frame. If I were in your shoes I would order a new oversized slide and fit it to the frame mine was only a four hour job.

[@EngineersArmory]

Ah heating the frame makes sense. Does anyone make bare 2011 frames with oversized rails?

[@loupuleff571]

@ normally you get the slide oversized and fit to frame but you’d have to measure your frame to make sure the slide is bigger dimensionally seems like your gun is a bit out of spec but not sure if it’s all in one of the parts or both ?

[@SPIN1963_]

@@EngineersArmory You can order anything from several frame suppliers (phone circus). The real issue is that aluminum frame ... I do not use them in my builds. Accu rails also have their own particular issues (time $ponge). Now if you want to build a carry gun that is not shot , that is a different issue. 2x bright = .5 long. Also a "Lip Gage" is critical ... used in the canning iindustry. I had two custom lip gages built for me ($$$), well worth it to me.

[@celmer6]

​@@EngineersArmorya quick Google Search will find you a world of 2011 frame's available. I picked a 80% complete frame and then decked it, drilled my hammer and sear pin holes, cut the barrel seat and cut the frame rails. It's a lot of work but I have the tight target 2011 that I have wanted since the 1980's and it's a great addition to my custom 1911 target pistols.

[@EngineersArmory]

@@celmer6 that's cool! Sounds like a fun project too!

[@FPSsuper]

Very interesting. Thanks for making this video.

[@Weapons_Appurtenance]

Very cool. Excellent video.

[@EngineersArmory]

Appreciate it! Thanks for watching and commenting!

[@markcooper9063]

You can put a set screw where the barrel seats in the slide adjust the set screw to stop the barrel in the same place everytime viola acurized 1911

[@aMcConghie16]

Great video, yeah I’m definitely not hitting my slide with hammer. I would by a different slide and file it to proper specs. God I love 1911s such an epic firearm!

[@hopewilliams6705]

These are the kinds of video channels Brownells needs to sponsor! But this isn't high flying super sexy content. But Super important

[@EngineersArmory]

Yeah I agree, someone give me money for what I am currently doing for free! haha

[@annihilationsquares1113]

Well this was interesting. Thanks for sharing!

[@EngineersArmory]

Glad you thought so!

[@strangisproductions]

in the middle of a weld up myself .. definitely a lot of work .. but I think it’s the best solution for a tight slide/frame.. you have to get a very good welder or be one yourself …

[@EngineersArmory]

That's dope. Would love to hear how it turns out for you. I dont have a good welding machine, nor am I a good welder haha.

[@Riley_1955]

I've owned many a 1911 and I completely agree if you want a tight slide to frame fit just pay for it.

[@customcutter100]

Great video. I'm actually surprised that you were able to swage the lower by using the "punch" with 2 or 3 stacks of aluminum plate under the frame. But then again we aren't talking 60 rockwell knife blades. Probably closer to 40 rockwell for the frame and slide. Any chance that you could have swapped the Mac9 frame and Tisas frame and got a tighter fit? I know my Mac 9 "rattled" a little more after stoning and polishing everything. Just picked up the Tisas last Friday and put a few rds through it today. Grouping was better than the initial Mac 9, but I think the trigger is 4.5# vs 6-7# on the Mac 9 before I started adjusting it. I might try swapping the slides on the two and see if there is a difference in the "rattle" test. LOL Thanks for sharing Ken

[@EngineersArmory]

yeah the frame material was not that hard. You're right probably around 40 Rockwell C. To swap the frame out and get a tighter fit, the individual frame being swapped to would need to be measured to see if it will actually fit tighter with the dimensions of the new slide. Could be a toss up. Pretty easy way without measuring would be to put it on and see how much it rattles haha.

[@toddb930]

I would like to try the weld up rail approach. I need to find a TIG welder I could trust first.

[@EngineersArmory]

Yeah I have the ability to the machine the rails as needed. The welding would be the problem for me too.

[@markcooper9063]

The barrel going into battery in the slide everytime is the most critical

[@EngineersArmory]

Barrel lockup in the slide contributes more to accuracy than slide fit for sure. The Kuhnhausen manual states that slide to frame fit accounts for only about 15% of pistol accuracy.

[@speedyx8988]

So I gotta know. Did you achieve a 15% grouping improvement? Cool project! I love all my 1911/2011’s but I would never squeeze my slides in a vice. Way too scary!!!

[@EngineersArmory]

Did not test accuracy before and after as that wasnt important to me.

[@hopewilliams6705]

Maybe if you had a wider tool to beat the rails down? I have often thought about this process myself but don't nearly have the tooling

[@EngineersArmory]

The problem is that the rails are only .060 wide. There would be no point to beating down the metal that isnt above the rails. It would also make it harder to squish down with more contact. I do have a double sided swaging punch and I bet that would produce better results and be more repeatable. But since it would swage down both rails at once, again it would likely take way more force. This was already scary and hard enough haha. i would have also had to buy two fitting bars.

[@hopewilliams6705]

@EngineersArmory yeah could it be done with care and a press? Probably not

[@EngineersArmory]

@@hopewilliams6705 That would have to be a gnarly press. With a very stable bed and fixturing. I doubt an arbor press would work. Would likely take hydraulics.

[@CyberTankMan]

👍

[@jeffreygoss8109]

I’m expecting the next video to be heat treatment to relieve stress and some final coating process

[@EngineersArmory]

Haha you are going to be disappointed. Done with this project it wasnt fun.

[@jeffreygoss8109]

I have seen watchmakers use laser welders with great accuracy for very precise fit requirements. It was for aeronautical purposes on inconel. I think they tacked on bronze too to be the sacrificial material. But I know you are just taking a challenge for fun

[@EngineersArmory]

Micro welding with a laser and re machining would be best. When I was doing R&D for a tech startup we got some micro welded nickel sleeves for embossing a microstructure. The weld was 125 microns wide and under a microscope looked like a roll of nickels. Truly beautiful.

[@jeffreygoss8109]

@ some people have skills…I do not.

[@EngineersArmory]

@@jeffreygoss8109 I can cut my way in and weld my way out of some heavy equipment with a wire feed. I wouldn't dare try to weld 1911 frame rails.

[@titter3648]

Why not just strip or mill off the anodizing just on the rails, and then electroplate a layer of copper on the rails until you have enough thickness to get the clearance you want? Should be pretty simple to do because the rails sticks out from the rest of the frame so you can just submerge just the rails in the electroplating solution and keep the rest of the frame above the liquid.

[@EngineersArmory]

Very interesting idea I didn't think about! I wouldnt recommend plating with copper, that is a soft, gummy metal that does not work well for applications where abrasion resistance is key. I have seen bronze brazed onto hydraulic cylinder pistons as the wear surface instead of composite wear rings. Those reciprocate much much slower though. I have played with electroless Nickel plating. That is a hard, abrasion resistant coating. However it would be hard to build up enough thickness to replace the anodizing that was milled off and then some to take up clearances. I think it would be feasible to machine off the anodizing, then get a skilled welder to add aluminum material to the rail surface to be machined back.

[@titter3648]

@@EngineersArmory Copper alloys is the most popular bearing materials out there like brass or bronze. And bullets have a pure copper jacket that is a bearing material used at really high speed against the inside of the steel barrel when the bullet is fired. And even better the copper will wear before the steel rails in the slide. So when the plating eventually wears away you can just re-plate it while the slide rails is still good as new. If the frame is made from high a strength aluminium alloy like 7075 it is not possible to weld. And unlike plating you can not finely control a weld's thickness so you will have to machine the rails back in after welding, while with plating you can just plate it in multiple steps until you get the desired thickness without having to do any machining after.

[@EngineersArmory]

@@titter3648 I am aware copper alloys are used for lots of bearing surfaces. I disagree that it is appropriate to use in the application of pistol frame rails. Generally alloy friction bearings in high speed/cycle applications are hydrodynamic and ride on a thin film of pressurized oil. The example of a bullet is not very applicable here - it gets fired once and it has done its job, it is not cycled. Its more to seal the bore so the expanding gas can propel the bullet, and protect the soft lead core from coming apart. (of course there are hard cast lead bullets that dont require a jacket). Certainly feasible to plate the rails with a copper alloy, but I would imagine it would wear very quickly and need re-plated. I would be really curios to see how many rounds it would take before the clearances opened back up though... Properly fit, uniform slide and frame rail interfaces, steel, or anodized aluminum will last a long time, ,thousands of rounds. Another problem with electroplating is charge concentration at sharp corners and discontinuities (like on the frame rail) - they would have uneven deposited thickness around the corners. Thats why I mentioned electroless plating - it is catalyzed by heat and deposits on whatever geometry the part is evenly. Right, most pistol frames are 7075, which cant be welded by conventional means - i forgot that. I still think Accurails are the only feasible method for tightening clearances on aluminum frames (horizontal clearances could be tightened by slide squeezing).

[@ghostshadow9046]

Anyone remember the accu rail system?

[@deleteduser3749]

Ever see that wire thing that cuts metal so when the pieces are together you can't even tell its been cut. Perhaps that could be used In manufacturing?

[@deleteduser3749]

Wire EDM

[@EngineersArmory]

As deleteduser3749 said, that is wire EDM (electrical discharge machining). It is a very common manufacturing operation. It would not be well suited to the application of cutting 1911 frame and slide rails.

[@deleteduser3749]

@EngineersArmory yeah. I later heard you reference it in the video. Some little video I saw though shows deep cuts in metal that are imperceptible to the naked eye. I don't know what that was...

[@EngineersArmory]

@@deleteduser3749 I've seen those too. They arent made out of one piece of metal. They start as two separate pieces and are machined to such tight tolerances they fit together and kind of "disappear into" each other.

[@deleteduser3749]

@@EngineersArmory wow. I shot a Kimber 1911 once. Felt like butter. I imagined the tolerances were super low; compared to the baretta I shot the same day... don't forget. Perfect is the enemy of good. Happy travels.

[@rogerray7820]

Place 12 standard size glass. marbles in an empty soda can and shake it will sound like your pistol! Moral of the story - but junk, get junk. But quality, get quality.

[@EngineersArmory]

You definitely get what you pay for with 1911s. Generally its best to pay more up front to get a better fit gun. I bought this gun knowing the slide to frame fit would be shit haha.

[@jeffreygoss8109]

Slap on some thick ass grease and hope you don’t find out it is flammable. 😂

[@EngineersArmory]

I should drill some grease passages and add a grease zerk on the top of the slide. Keep her greased and tight!

[@jeffreygoss8109]

@@EngineersArmorygood enough for my car’s suspension. 😂 just load it up until goop pops out the barrel. I love this channel.

[@P46345]

My sister wouldn't shoot a 1911 in 9mm.