Rotary Delayed Blowback: CMMG 9mm AR15 Upper On WWSD 2020 Lower

[@Chlorate299]

I have a soft spot for delayed blowback systems, the mechanical cleverness tickles me in the bit that is tickled by mechanical cleverness. I *really* like how they've managed to do it just by changing machining operations on otherwise standard parts, it does make the push-to-jam button that much more amusing though.

[@lockpickinglawyer]

Well, that was an unexpected opening… 😂👍 I’ve been considering updating my old cmmg mk9 SBR to either cmmg RDB or maxim’s RDB to shave some weight. It needs a frickin’ 12oz buffer to run suppressed without a face full of blowback! This was helpful… especially your thoughts on upping the buffer weight. Thanks.

[@TheStig505]

What kind of can do you run?

[@BlokeontheRange]

@lockpickinglawyer Aah! Funny when the person who I referenced in the intro appears! 😃 The one thing to watch out for is that some of them eat ejector springs every 1000-1500 rounds (mine does). I discuss that and the solution here: kzbin.info/www/bejne/d4vWq2aslLh_iqcsi=YhxWLmt8yQ40xfF4

[@rodrigodepierola]

"Bolt picking Bloke", I see what you did there.

[@KasperBoLarsen]

Indeed, I was slightly confused for about 2 secs there 😄

[@Gagis]

This thing is incredibly cool. But I made a mistake: I checked how much these cost in Finland. Yikes!

[@BlokeontheRange]

It was pretty "yikes" here too...

[@Scott-qq9jd]

So you are aware, I discussed it with CMMG, snd they said an ideal ejection pattern on one of these is ejecting to 3:00 to 3:30, and a 4:30 means the bolt is traveling faster than is ideal.

[@BlokeontheRange]

Thanks!

[@Scott-qq9jd]

@@BlokeontheRange Glad to help.

[@BlokeontheRange]

Do they have anything to say about the extractor dropping cases?

[@Scott-qq9jd]

@@BlokeontheRange I haven't asked, but CMMG has had some QC issues the last couple of years, and extraction issues are the usual result. Mine has yet to have any issues, other than one odd experience when I manually chambered a round and the bolt missed picking up the next round and then got stuck on that round. Only malfunction in many rounds.

[@BlokeontheRange]

There's lots of discussion on forums regarding uprating the ejector and extractor springs. The ejector spring in mine is really soft compared to the Oberland Arms one I was comparing it to, and apparently CMMG have been giving people the ejector springs for their 10mm ones as a fix. So I really hope the Tubb spring set fixes it :)

[@MrS22222]

Love my cmmg upper, it really does tame the blowback a lot and stays much cleaner.

[@That_Guy5575]

I was really excited when I saw this video, this is the exact setup I’ve been wanting for a while! Very happy you put this video out!

[@libertyrevolutionary1776]

Not just in 9mm, but in 5.7x28, 4.6x30, and multiple other pistol cartridges.

[@lonsmithwesson1661]

I run a linear compensator on my blow back AR9 and quite enjoy the lowered perceived report, with a 16 inch barrel the complete powder burn and still sub sonic 124 grain load I run it's quite pleasant.

[@desmendETKILLAZ]

Lol I like your reference to the lock picking lawyer

[@derekmartin2817]

I have a ke 9mm blowback ar. Some tuning things that help run those (i know its different than radial blowback). Are 5/8 inch spacers behind or longer vltor a5 buffers. The a5 buffer is also able to be heavier. You don’t need as much stroke to eject 19 mm brass as 45. For blow back i also use a 308 spring. I have a picture comparing it to a standard ar buffer and spring, but I couldn’t figure out how to post it here or patreon.

[@BlokeontheRange]

The CMMG mags seem to present the rounds a lot further back than the Glock mags commonly used (not had the chance to compare side-by-side) so the bolt does need a bit more travel :)

[@dbmail545]

Blitzkrieg Industries sells an AR-10 buffer spring and hydraulic buffer combo that really tames AR-9's.

[@mlone7]

@@dbmail545 I run the KynShot 5007 hydraulic buffer with a Tubb 556 flat wound and an A5 buffer tube.

[@kencooper74]

CMMG sells a kit that has a few weights that help you tune the system. JP makes a 9mm specific buffer system that is also available as a kit. I do think you need more weight in the system, that bolt is moving very fast.

[@BlokeontheRange]

The JP 9mm specific system shortens the bolt throw significantly, I looked into it. Probably wouldn't work with the converted P-mags. Since filming and editing, I've tried a 5.4oz conventional buffer and it doubled the reliability. I reckon that with more powerful springs for ejector and extractor we should be able to nix the last bit of the .case-dropping thing.

[@stevailo]

@@BlokeontheRange maybe some of the jp weights in the standard jp scs you already have in your WWSD lower might help?

[@kencooper74]

@@BlokeontheRange That makes since, the CMMG bolt is longer than a blow back bolt. The converted P-Mag holds the rounds to the rear of the mag and away from the chamber.There is a company called Heavy Buffers that sells an 8.5 oz standard length carbine buffer with a wolf heavy spring that will probably work for you. I use their 8.5 oz 9mm buffer setup in my 10.5 in barreled 9mm AR. With the Mean Arms P-Mag conversion mags it is very reliable.

[@lettiprkl2050]

@@BlokeontheRange I have JP 9mm short stroke -version and it works just fine with those ARC9 magazines, I think I've done about 3k rounds with it so far. When I first got the rifle I shot about 2400 rounds without cleaning the rifle and even then I only cleaned it because it was National Championships next week... yours looks pretty clean to me! :)

[@Baltimoreed]

Also having ejection issues with my cmmg’s. Ran great when brand new. Going to get a stronger ejector spring and extractor spring and see what happens.

[@t.dubbya7000]

Very common issue with these weapons.. They eat ejector springs. once the cases start ejecting strangely, or even dribble out the spring is probably due for replacement. The dissent fixed this issue with a static fixed ejector , but you lose a lot of the tunability the buffer and spring provide the platform.

[@TheRealRedRooster]

That "lock picking lawyer" spoof at the beginning had me choke on my dinner, didn't expect that.. LOL

[@t.dubbya7000]

Very common issue with these.. They eat ejector springs. once the cases start ejecting strangely, or even dribble out the spring is probably due for replacement. The dissent fixed this issue with a static fixed ejector , but you lose a lot of the tunability the buffer and spring provide the platform.

[@itsapittie]

"The button of doom" 🤣🤣🤣 That's pretty much how I feel about it. The forward assist is a pointless solution to a problem that doesn't exist. I've used Aero Precision "no forward assist" uppers on my last two builds and will probably do so with all of them going forward.

[@LadyAnuB]

Bloke, does your WWSD rifle also play What Would Brian Boitano Do? as well?

[@BlokeontheRange]

It should have a music chip fitted to do that! :D

[@LadyAnuB]

@@BlokeontheRange Get on it man! Modify this rifle even more. 👍

[@mattpeacock5208]

I know one thing, He'd kick an ass or two! That's what Brian Boitano'd do!

[@stewbacca117]

I too was subjected to the 'orrid L98A1 and its crank handle organ grinder desperation... The kids these days don't know they're born with their semi auto only variants. I like the fact they use the PMAG footprint just converted to feed 9mm, looks like they have a long shallow feed ramp built into the mags to aid feeding reliability too?

[@BlokeontheRange]

Yup, it's basically a plastic chute that funnels the rounds so that they're presented from a single angle. Never had a feed issue, only ever that ejection one. It's actually just an insert in a normal P-mag body.

[@jefflemaster2850]

They do have the feed ramp built in to the conversion inserts. It’s a really nice system. There are two versions one for the CMMG that doesn’t have the ejector, and standard 9mm BCG version that has the ejector as part of the conversion.

[@junglesairsoftblog6311]

My experience with the Cadet GP was similar, I remember watching instructors walking down the firing line with a fairy liquid bottle filled with gun oil squirting a line of oil down the rail of every cocking handle just to keep them running, they must have used gallons of the stuff.

[@0Asterite0]

One guy on arfcom had his gun set up with a fixed ejector and ended up running very reliably

[@neil2983]

I'm particularly surprised theres no angled machining on the rear of the barrel extension on the upper you received. Is this consistent with what other owners have discovered do you know? Cos my knee jerk reaction( given the patent info you showed )would have been they've fitted the wrong barrel in ya upper.. or that the manufacturers gone cheap on their customers..that initial amount of travel you demonstrated upon applying force to the bolt head with ya pokey stick seems a bit gash doesn't it? Wouldn't that initially movement be under pressures even higher than a hand gun 9mm with a tilting barrel for example? Makes myself curious if the whole angled surfaces business is a bit of a marketing blag and its simply no dwell on the cam pin surface that's actually doing the work..

[@fermantravers5478]

Thank you for this in depth educational video. Did changing to a stiffer bcg spring and ejector spring resolve the ejector jams, and did you replace your stock charging handle with a Radian Raptor, LT, or SD? Cheers Mate!

[@BlokeontheRange]

Yup, I did manage to fix it. Here's the entire discussion: kzbin.info/www/bejne/d4vWq2aslLh_iqc I've actually swapped the T-handle with a Schmeisser one from a straight-pull after getting bonked in the nose by the big one annoyingly during a competition.

[@mabs9503]

Hey I'm planning to build basically this so thanks for the info.

[@simonjones6128]

Good job Mike

[@eugenejensen2279]

You can get a weight set for the BCG. The weight goes inside the BCG using a role pin. You can get them from Midway USA it slows down the BCG so you don’t have that ejection and feed jam issue you had in the video. I am using the middle weight in my 16” uppers. The heavy weight in my 8” pistol uppers. The weight kits come with three weights in them and one roll pin.

[@BlokeontheRange]

I fixed it by putting in a quality ejector spring. It needs replacing every 1000-1500 rounds though, unfortunately...

[@tommythetrain1945]

Also the weights are for suppressors i think

[@mlone7]

I run a Tubbs 556 flat wound spring, with a Kynshot 5007 hydraulic buffer, and an A5 buffer tube. It makes the cycle speed slow slightly but softens the recoil to where it rivals the softness of the HK MP5. Give that a try and see if your cycling issues go away. I have never had any cycling issues with this setup

[@BlokeontheRange]

I fixed it with a Tubb ejector spring. I do have to replace it every 1000-1500 rounds though, unfortunately...

[@mlone7]

that is unusual to have to change that spring so much. I would try the rest of what I am doing and see what that does for you.@@BlokeontheRange

[@mlone7]

@@BlokeontheRange I forgot to ask you if you are using steel cased ammo in that gun?

[@BlokeontheRange]

@@mlone7 nope, brass. Specifically 115gn Hungarian made Geco

[@thewidgetmachine]

Well this got a lot steamier than expected, with all this talk or buts on the floor and giving them some umpf.

[@johnstacy7902]

Great Googly Moogly I have to run a 308 buffer spring and a 8 Oz buffer on my blow back 9mm AR.

[@jefflemaster2850]

What BCG are you using? I’m running a KAK bolt on a 5 oz buffer and it seems fine. I did want to try a H3 just to see if it smoothed it out a bit.

[@SinistralRifleman]

.308 buffer spring and 8oz buffer is what I find works best for 16” blowback too. I also have a 7” shorty and it won’t run with 8oz, needs 5.5oz

[@jefflemaster2850]

@@SinistralRifleman ah- mine is an 8.5 so I guess the 5 oz buffer makes sense for my set up.

[@SinistralRifleman]

@@jefflemaster2850 yeah with blowback the longer the barrel the more back pressure the more weight for the buffer

[@mattiaseriksson6422]

Nice!

[@mattiaseriksson6422]

The LPL inspired intro, loved it😀

[@BlokeontheRange]

I kinda needed an excuse not to bother with a talking-head-to-camera intro and outro so thought I'd make a tribute to LPL :D

[@tomunterwegs1206]

i remeber it beeing called radial delayed but both are right, i guess. but damn, the combination is effectiv!

[@LadyAnuB]

@@BlokeontheRange Why not go full LPL and give us an under 2 minute video?

[@saoirse5308]

Bloke, this is in no way a criticism, but rather an honest Question. Why is your red dot there? I am new(ish) to red dots and I find people mount them up and down the rail. The owner of KE (That lower if I'm not mistaken) Mounts his red dots a good 4-5 inches farther from the eye then you have yours. Is this all just personal preference? Or are there mounting points based on shooting styles that I just don't know about?

[@BlokeontheRange]

I'm never, ever going to put a magnifier behind it, and I like to see more of the world through my dot. On my WWWSD upper it's further forward, cos I have a magnifier. When I've got the 2 uppers matched, I *might* put the red dot further forward so it's exactly the same, I might not. I think the fashion for putting them forwards came first from the Aimpoints on gooseneck mounts, and then from compatibility with magnifiers. But the thing with them is that you can put them wherever you like cos they've got no eyebox so no eye relief restrictions.

[@SinistralRifleman]

The further back your optic is the easier it can be to acquire from unconventional shooting positions. If you’re not using a magnifier or BUIS mounting it all the way back can be faster/easier to acquire.

[@saoirse5308]

@@BlokeontheRange Thanks, that makes sense, I hadn't considered a magnifier

[@saoirse5308]

@@SinistralRifleman Thanks, I guess I'll start there and see how I like it. 👍

[@thomkatt]

When you going to do a full video review of your personal WWSD?

[@BlokeontheRange]

Yup, when I've got some footage of me shooting it and spent some more quality time with it.

[@erg0centric]

Seems like it would be a bit hard on the locking surfaces, good thing it's pistol calibre.

[@flyerh]

From that I am assuming the Lantac straight pull 9mm for the UK rules does not have the angled cuts so that the shooter has to pull back on the bolt similar to the .223 battery design without a gas tube?

[@BlokeontheRange]

The Lantac stright pull 9mm just has a standard AR15 BCG modified for the charging handle: kzbin.info/www/bejne/Y3XbnWpqeZd7Y9E

[@rickoshea8138]

Mike, I hope this is not a rude question, but can't help wondering what your day-job is? I also can't help wondering if conventionally locked breech piston system could be made to work in a 9 mmP AR-15. Perhaps with the gas tap much closer to the chamber, like on an M1 Carbine.

[@BlokeontheRange]

You may keep wondering! :D You could probably get a short stroke piston to run if the gas tap was right in front of the chamber. There's just soooo little gas at such a low pressure (comparatively) with 9mm compared to rifle calibres, but the question is really why add the complication when you can just go blowback? You could even in a pinch use a conventional AR15 bolt head arranged so as not to rotate, although that would be not optimal and would defeat the inherent out of battery safety that the Stoner-type bolt system provides.

[@rickoshea8138]

@@BlokeontheRange Yes. A rude question, and a polite answer. Thanks In blowback, you have the inertia of the projectile "pushing" against the bolt inertia + the average gas pressure pushing on the case area. So, the case is acting as a piston - case to chamber friction. So, I think it would be possible to tap into that same gas pressure to use a larger than typical piston diameter (10 mm like the case) to make a locked breech work. The gas tap must not be so close to the chamber that the bolt starts rotating before the bullet leaves the muzzle, but enough impulse is available in blowback, therefor must be available to operate a locked breech system. Another way would be recoil operated rotating bolt, like the M4 Benelli shotgun. Else, blowback seems and OK system - it is used in 9 mm SMGs all the time; although most of those fire from an open bolt - and their bolt (or bolt + carrier) are heavy.

[@BlokeontheRange]

Inertia doesn't push against anything, it's simply what a mass has and is a scalar quantity ;) But I think you've answered your own question as to why you wouldn't bother. But 10mm would be rather excessive. Also, 9mm has nowhere near enough recoil for a Benelli-type inertia system (Benelli M4 is gas operated btw ;) )

[@rickoshea8138]

@@BlokeontheRange Mike; Asking you a personal question is like you asking if my real name is ricochet? No, it is a pseudonym. What makes me wonder about you is that you are very knowledgably, well spoken, and enthusiastic without any grand airs or posturing.

[@BlokeontheRange]

I'm a bit coy about what I do in the day job cos it makes me doxxable by people who are ill-inclined (not that I think that you are, but it's a general principle that I keep it close to my chest... But let's just say that there's a crossover in the skill set). And thanks for your kind words :)

[@johnbrennan3735]

I'm thinking you're in the UK, if so how in the world did you manage to get a WWSD? I really appreciate when people design in fail safes where parts just will not go together wrong. Great video, thanks for the detailed breakdown, very insightful.

[@BlokeontheRange]

You're thinking wrong ;) Thanks for the kind words!

[@DebakulumToughguts]

👍 für den Algorithmus

[@hanktorrance6855]

Always interesting, your perspective and insights are different from anyone else doing reviews !

[@christopherberry4452]

Such a cool set up. A suppressed sbr In this setup would be dope!

[@Scott-qq9jd]

I'm waiting on a tax stamp for a suppressor so I can do exactly that. I have the version with a 5" barrel, and I've added a three-lug adapter up front.

[@edgarburlyman738]

So the cmmg 5.56 is NOT radial delay? I was wondering that. It's not very clear on their website.

[@BlokeontheRange]

They call it "radial delay" for some reason. But nothing is acting radially, and it's the rotation of the bolt driving the carrier back via the cam stud that generates the delay.

[@onpsxmember]

Any alternative that isn't as dirty for pistol calibers? Is the buffer setup that was shipped usually for a much shorter barrel?

[@magoid]

I believe SIG's PPCs are gas operated? Those may be more cleaner.

[@BlokeontheRange]

It wasn't shipped with a buffer, it was bought just as an upper and didn't come with a buffer.

[@robinpage2730]

A 4 lug bolt would work much better for this system. More surface area to act on, longer delay, safer operation. It's basically just a rotating version of the lever delay blowback system.

[@dbmail545]

I have an AR-9. The 16" barrel seems to waste many of the advantages of a PCC. I wonder if the RDB action is less brutal on the lower than a straight blowback action. My PCC has had more broken parts than it had with 10,000+ rounds of centerfire rifle cartridges.

[@mobiljobe]

It should be less brutal as it is much less reciprocating mass. I have run my cmmg with standard ar15 spring and buffer and it does not seem run any rougher than a standard .223 AR15.

[@Grasyl]

14:06 Normally blowback operated firearms do not need an extractor to operate*, because the case is being pushed out of the camber by the gas pressure in the barrel. The main problem is that the Banshee is a system designed for passive extraction (AR-15, M16) now converted to active extraction. *Most blowback firearms only need the extractor for guidance of the self extracting case or for manually extraction.

[@BlokeontheRange]

All it's doing here upon firing is supporting the case and providing a pivot point for ejection, indeed :)

[@oldmanSturzl]

I suppose it would also help with clearing the chamber of a live round.

[@GunFunZS]

So if the ejector pin had a shoulder, it could bottom out on something other than the spring.

[@BlokeontheRange]

Its hole has no corresponding shoulder. You could have it bottom out on the pin by cutting the notch differently, but that would probably just mash the pin.

[@danielroesner2342]

I am looking for an upper like this for a Long time in switzerland but they are all horribly expensive- where did you get it and how mich was it?

[@BlokeontheRange]

Aebi and it was 1800.-. So very pricey! He doesn't have any more 18" ones though...

[@danielroesner2342]

@@BlokeontheRange Thanks Mike. Aebi is next door to me, but 1800 for an upper.. Naaaah

[@abitnutz6747]

Why does KE Arms have this warning about using CMMG uppers on their website? "CMG Radial Delayed Blowback Uppers will need modifications to the ejector to work." What ejector problem are they talking about?

[@BlokeontheRange]

There's a follow-up vid where I fixed mine. In my case it needed a better ejector spring

[@ianvincent4911]

I have wondered how the UK straight pull versions work. I assume they replace the spring behind the bolt head with a solid spacer (or something similar), to prevent it from disengaging until you pull back on the bolt?

[@BlokeontheRange]

No, they are standard AR15 bolts / carriers and simply don't have a gas system.

[@ianvincent4911]

@@BlokeontheRange Is that the case for the 9mm versions?

[@BlokeontheRange]

I presume so. I've not seen the insides of one yet, and I'm absolutely sure they won't be based on the CMMG rotary delayed blowback system in any case.

[@ianvincent4911]

@@BlokeontheRange The T2 9mm uses these magazines (rather than Glocks), although they make their own bolts. I will have to have an engineering chat, next time I am down at the Tunnel.

[@BlokeontheRange]

It would be interesting to see if they did anything clever or if it's literally just mostly standard parts like I suspect.

[@asas-mb4wj]

hows it treating you now?

[@spraynpray]

A friend had one of these and sold it recently. It absolutely didn't delay the bolt. The bolt went too fast and was very jarring and unreliable. He sent it back and they said the bolt was out of spec and replaced it. Same story with the new one. Had to add a bunch of weight to the bolt so it was heavy like a straight blowback. Recoil was intense. Very unreliable. Ejection pattern was everywhere from 12 to 6 o clock using the same ammo in the same mag in every test we did. Brass often hit the shooter. Brass got a lot of soot on it. It was fired unsuppressed. I hated the thing. I bought a Stribog SP9A3 to test it out. It is delayed and has better mags and is a bit cheaper. Neither compare to an MP5. An MP5 or even MP5K with +p ammo is smoother than the Stribog with normal 9mm. A mule kicking me in the shoulder is smoother than that CMMG radial delay.

[@BlokeontheRange]

I've heard several horror stories like that - overall, mine shoots really sweet, and will be awesome if I can get the ejection competition reliable.

[@chickenfishhybrid44]

Adding the weight to the BCG with radial delay does seem counter productive. But I'd think the overall mass is still likely less than a standard blowback 9mm AR.

[@WojciechP915]

The default finish for WWSD rifles should be Hi-Point money.

[@WetWiIIy]

Nice. I would love one of these on my spare KP-15, but they're hard to find! Random admittedly nosey question: do you identify more as a Briton or a citizen of Switzerland? A Switon?

[@BlokeontheRange]

I'm not yet a Swiss citizen so I don't really have any choice in the matter ¯\_(ツ)_/¯

[@WetWiIIy]

@@BlokeontheRange Ah, well when that time arises and you've had some time to think it through, you'll get back to me then? Seriously though, much respect to the unique content you put out, and best of luck in your endeavors. You've chosen a beautiful country to call home!

[@johnstacy7902]

You'd think with the name Burns a fellow could consider himself a Scottsman...

[@BlokeontheRange]

The only Scottish in me is actually on my mother's side, and is a great grandfather. I guess in US terms that is enough to make me "scottish" though, lol :D :p

[@Scott-qq9jd]

@@BlokeontheRange There is an odd yet understandable tendency in the US to identify only with the "coolest" part of one's ancestry. The number of people calling themselves Native American based on a family claim of one Native American ancestor six generations back is... interesting.

[@mikesmithg0rfd356]

thank you

[@Ace1900-de3xm]

I have a question I got a AR-15 it's converted to 22lr to charge it or to convert it to a 9mm do I have to buy a upper only ??

[@BlokeontheRange]

yes

[@Ace1900-de3xm]

@@BlokeontheRange can I just buy a bolt carrier instead or I got get a whole new upper

[@BlokeontheRange]

@@Ace1900-de3xm if you don't buy a new upper, how is your 9mm going to fit down a .22 hole?

[@Ace1900-de3xm]

@@BlokeontheRange lol thank you I really appreciate it

[@momosgarage]

Will this fit on any lower?

[@BlokeontheRange]

Yes. Obvs you'd need the usual adaptors for the old-style Colt lowers (SP-1 etc.)

[@onkelmicke9670]

Yeah that hesitation lock

[@cedhome7945]

What is the optimum barrel length for 9mm velocity? Does it drop off significantly when you're using a long tube

[@hjorturerlend]

8-12 inches or so, generally. Don't know if it's significant, but it definitely does start to lose velocity to friction somewhere along the way. Odd decision, one of the few advantages pistol caliber rifles have is that they don't have the drawbacks short barreled rifles have.

[@rickoshea8138]

Search for: ballistics by the inch 9mm. It depends on the load, but peak velocity is reached as early as 12", and is then "flat" to 18". So, depending on the load, a 16" barrel is not costing you velocity. Certainly, a 16" barrel shoots 150 to 300 FPS faster than a 4" barrel, again depending on the load. I will post the link in reply to this comment, in case links are suppressed.

[@rickoshea8138]

I can not see the link I posted, after refreshing the page. That means you will have to find the BBI page yourself, based on the terms I provided.

[@BlokeontheRange]

Sorry, YT eats links cos it mostly presumes them to be spam... I'll see if I can shake it loose from the filter...

[@rickoshea8138]

@@BlokeontheRange I know some channels that allow links and others don't. I think it is at the discretion of the channel owner: You.

[@roflchopter11]

Any wear on the locking lugs in the barrel extension? Seems like the corners are getting hit by the bolt every shot. Does it stretch brass? 0.1" of straight blowback against a ~1oz bolt seems rough.

[@BlokeontheRange]

Given that 9mm is almost straight-sided, there's no reason for it to stretch. Don't reload it anyway so wouldn't care if it did :)

[@roflchopter11]

@@BlokeontheRange interesting. Doesn't the brass grip the walls of the chamber? Or does it all slide out together?

[@LuminaryCursorem]

I really want an AR chambered in .22 tcm

[@onpsxmember]

It'd make more sense than in their pistol that needs some work in the reliability department. It'd be less loud but I wonder about the barrel life.

[@cymond]

The AR Guy makes one, but I suspect they're expensive

[@cymond]

@@onpsxmember Barrel life shouldn't be any worse than 223, I imagine

[@jayheredia6975]

I’m lost. That’s not a 9mm BCG right? How is it shooting 9mm?? I’m having problems with my ar9. I have a 9mm bcg

[@BlokeontheRange]

Yes, that's a CMMG delayed blowback 9mm BCG

[@jayheredia6975]

@@BlokeontheRangedoes the cmmg BCG only fit in cmmg 9mm complete upper or no?

[@mlone7]

@@jayheredia6975 You have to have the BCG matched with the delayed blowback barrel. It will not work with a straight blowback barrel like you have.

[@jayheredia6975]

@@mlone7 thanks for the info. Yeah I learned a few months back about how cmmg works Nd it’s def over priced for even the most simplest product. I returned the cmmg BCG Nd just just a regular 9mm BCG Nd use Glock mags

[@NomadShadow1]

Cool

[@automandan]

Interesting.

[@steher]

Position of the optic . . .

[@BlokeontheRange]

I'm not going to use a magnifier or BUIS and I like to see more of the world through it. I know it's fashionable to put them forward anyway, but I don't care about fashion.

[@mattpeacock5208]

The problem lies in the fact that the Stoner system was intended for rifle rounds operating at 50,000 psi+. Altering it to work with pistol rounds means you literally have to cut corners. Just stick with good ole 5.56!!! IMHO.

[@BlokeontheRange]

And on ranges only rated for pistol calibres? Or compeitions obliging pistol calibres? ;)

[@mattpeacock5208]

@@BlokeontheRange they make dedicated carbines for 9mm if that's your poison.

[@BlokeontheRange]

Why would I want some dedicated carbine when I can have a 9mm AR matched to my .223 one so it feels as similar as is humanly possible, so all the handling, controls etc is exactly the same? ¯\_(ツ)_/¯

[@callhoonrepublican]

Does it recoil more than the 5.56 like a blowback 9mm? Or is it about the same or even less?

[@BlokeontheRange]

It's difficult to say, the impulse is a bit different compared to the WWSD with A2 cage. Similar with 115gn, a bit more with 124gn I reckon. With a decent brake that actually works it should be really, really sweet.

[@Scott-qq9jd]

I would say mine definitely recoils less than an overgassed 5.56.

[@callhoonrepublican]

@@Scott-qq9jd that's the interesting part. 5.56 ARs can very wildly in recoil. I shot an anderson that was so over gassed it almost felt like shooting .308

[@urkince26]

Who just casually has an AR barrel extension laying around? 🤣

[@BlokeontheRange]

Someone who'd been planning on using one in a video for about 2 years so ordered it ages ago!!! There's another video in the planning that I'll use it for :)

[@blindprophet182]

Half the weight as the sp5 with a long barrel and alot less ugly.

[@joshuamccallum2341]

Move your red dot forward.

[@BlokeontheRange]

No. Why should I?

[@joshuamccallum2341]

@@BlokeontheRange Do you shoot your red dot with both eyes open?

[@BlokeontheRange]

Yes

[@SinistralRifleman]

Look up Eric Lunds article “Inside the Ring”. There are advantages to mounting it further back.

[@BlokeontheRange]

I like being able to see more of the world through the dot, and having more space around the ring in the Holosun reticle before seeing the tube. My dot is further forward on my WWSD upper, but only so I can use a magnifier, and it's simply the eye relief on the magnifier that's determined the position of the dot (otherwise it would be back like on the CMMG or my M17S). When I've got the CMMG running reliably enough, and when I've got a KE carbon fibre handguard on it so it's basically matched to the WWSD, I *might* consider putting the dot in the same place on both so everything's the same. But, I like the dot close to my eye for the reasons already given :)

[@clearly_2967]

Will you be coming to woodland brutality this may bloke?

[@BlokeontheRange]

I'm hoping to! Can't guarantee it yet though...

[@billbailey1620]

why not make it gas operated

[@BlokeontheRange]

Cos there's not enough gas from 9x19mm to run the normal AR15 gas system, and it adds a lot of extra parts and complexity to do it with a piston (see SIG MPX).

[@billbailey1620]

@@BlokeontheRange load it real hot

[@billbailey1620]

@@BlokeontheRange the sig taps it right after the chamber

[@BlokeontheRange]

The SIG has a completely re-designed upper receiver, barrel, basically everything, in order to use that gas tappet in front of the chamber. Which needs periodic disassembly of the barrel and gas system for cleaning. "Load it real hot" means selling a gun which won't work with most ammo. The CMMG solution uses standard uppers, standard barrels, standard everything except bolt and carrier, so is a very economical solution. SIG uses bespoke parts for practically everything in the upper, including the upper receiver itself.

[@John-ro3vu]

While I think the Radial Delay sounds awesome, I was honestly pretty underwhelmed when I shot an acquaintances 10mm Banshee.

[@herknorth8691]

In what way were you underwhelmed? Did it not work well?

[@chickenfishhybrid44]

Have you shot a straight blowback 10mm AR to compare? If not, i can imagine it's harder to understand the point.

[@ABCantonese]

LAPD just had a case where an officer with a M4 missed, shot through the wall, and killed someone else. This would be a great option for cops already carrying M4s for indoor situations where you don't need reach and can't afford over penetration. Put on the upper and mag that the situation needs. Cuz I'm sure no PD is about to switch to 300BLK. The CMMG gives a smaller logistic footprint.

[@ericblank9956]

if .223 is shot through a wall it starts tumbling quickly reducing velocity but 9mm(and 300BLK) keeps going straight. Hollow-point bullets don't expand in hard materials if they did 9mm would be better.

[@roflchopter11]

9mm will over penetrate as well.

[@SlavicCelery]

@@ericblank9956 Not to mention, the move to .223/5.56 was due to body armor appearing in a notable shootout. 9mm doesn't solve that issue, so you'll still need the 5.56.

[@ABCantonese]

@@SlavicCelery I'm not advocating abandoning 556. You totally need it for outdoor or armoured scenarios. I'm just saying, have an extra CMMG upper in the car, so you can switch it out if you're running into an indoor situation.

[@ABCantonese]

@@ericblank9956 There is a large selection of 9mm bullets out there. Choose the right one and you can definitely reduce overpenetration. This was an indoor situation. Walls are typically 2 sheets of drywall. Sure that isn't enough for 9mm JHP to expand and dump all of its energy, but 556 by its nature is that many times faster and thus that many times more dangerous.

[@geezerp1982]

could you review the schmeisser 9MM PCC ?

[@IDK_what_TO_call_IT_]

Rotary delayed? Lol. It's RADIAL delayed. It's quite easy to find what it's called. Ive never even heard "rotary". 😂 like the phone? Good ol rotary phones.

[@BlokeontheRange]

They call it "radial" delayed for some inexplicable reason*. However, there's literally nothing acting radially, it acts in rotation to generate an amplified axial movement via a cam track. Show me on the doll where there's anything acting radially in this system. *I had a theory regarding trade marks, which are not allowed to be descriptive, so thought that "radial delayed" might have been thought of as some fancy name. Then I looked up the case history of their first attempt at registering RADIAL DELAYED BLOWBACK in the US, and they didn't make that argument resulting in the application was refused. So it wasn't that...

[@IDK_what_TO_call_IT_]

@@BlokeontheRange from the patent - A plurality of radial locking lugs are configured at a rear end of the bolt and seat within a mating profile of a barrel extension of the firearm in a fully chambered position. Regardless of that though, that's what it's called. Really wouldn't matter if they named it fuckial delayed. If that's what it's called that's just what it's called. Plus, rotary delayed just doesn't sound good at all.

[@BlokeontheRange]

The locking lugs extend radially. Just like a normal AR-15. They don't *act* radially though. They act rotationally. But well done for searching the patent for the word "radial". Also, that statement from the patent isn't reproduced in the product: the locking lugs don't seat within a mating profile in a fully chambered position: the first 0.1"-ish is unsupported and straight blowback, and there is no mating profile, the barrel extension surfaces are AR15 standard. So the inclined surfaces on the back of the bolt lugs cooperate with the corners of the splines on the barrel extension. Anyway, imagine if you made a video on HK-style roller-delayed blowback and some "well ackhtually" type came into your comments and said "well, actually, it's not roller-delayed blowback cos HK calls it "schminkenfinken halbstarre Verriegelung" even though it's blatantly not...

[@IDK_what_TO_call_IT_]

@@BlokeontheRange not gonna lie, I'm not reading all that. The fact is, the lugs are radial. Those radial lugs are delaying the blow back. Unlike an ar15. Just because the bolt heads look similar does not mean they act the same or perform the same. I really dont know why you're fighting this so hard. You acted like the term radial here was just inconceivable. We've proven that to be not true. So now you're just fighting it because you really like the stupid term you've come up with? Lol. It's pretty dumb dude. Just give it up because you've lost this one. It is what it's called and it absolutely has merit to be called that. Whatever arm chair engineer you think you are just isn't shining through on this one bud. Edit- and that hk comparison i just caught as i glanced only proves my fucking point. Lol. You don't see that? Even hk calls it roller delayed. YOU'RE the one trying to rename it. Lol. The fucking irony is palpable.

[@BlokeontheRange]

OK, so we'll call a normal AR-15 "radially-locked" then, since the lugs are radial, even though the locking acts axially. Got it. And HK correctly describing their roller-delay vs. CMMG being wrong isn't quite the own you think it is (cf. the common, misleading term "roller-locked blowback"? It's not locked, after all...) Terminology matters, and jargon terms that are misleading when given a plain reading are not helpful to anyone. I've seen people lose patent applications and fail to be able to enforce patents due to this in my dayjob since a misleading jargon term was used in an independent claim, so I will absolutely die on this hill.

[@F1lmtwit]

Does it need the buffer tube? (It looks like it does, but not 100% certain)

[@BlokeontheRange]

yes