Has anyone swapped out a CMMG 9mm Guard BCG and barrel in their current rifle?  Just wondering if anyone had any issues running the BCG/Barrel combo with any other brand of upper and lower.  Gonna stay with the Glock mag.  I read someone was messing around with the combo in a Colt mag pattern upper/lower but I’m not up for that challenge.  CMMG has both the Barrel/BCG combos for the 45 and 9mm in stock.  Way to go CMMG for releasing components.  One of the most innovative and forward thinking AR manufactures in the industry.

There are a couple of threads on the Brian Enos forum in Pistol Caliber Carbine - Technical about the Guard that addresses that.  Only thing that seems to be a consideration is a mag insertion stop.  The CMMG guard lower is milled for that.

I have a 9 mm guard, 16 inch rifle, and after seeing how it all went together, I ordered a barrel, BCG and lower to do another build.

Interested in this as well. I see a member doing it with a colt mag block, but I am wondering about using  a NFA/Joebobs glock lower or the new Stern glock mag block.

The guard bolt and barrel will eliminate everyrhing I dont like about 9mm ARs.

Just a quick update.  I purchased a 9mm Barrel/BCG directly from CMMG.  I dropped it into an upper and put it on a PSA forged LRBHO 9mm Glock lower.  That lower has the mag over insertion block as part of the design.  All you need to do is remove the ejector.  Function is 100% with brass ammo.  I tried some steel case Tula and had a couple issues.  Tried both ETS and Glock mags.  Both worked perfectly.  Also installed a buddies Franklin BFS and DIAS both ran equally well.  Standard carbine buffer worked well and was nice and smooth.  Hydraulic buffer was very smooth but longer and did not allow the bolt to be locked back using the bolt stop.  9mm buffer 8oz from PSA ran but had significant forward recoil (the whole reason I am trying to go to the new CMMG radial delay system).  I ordered an Armaspec quiet buffer for the setup and hope it runs well.  Suppressed seemed to reduce port noise and very happy with perceived increase levels of suppression at the shooters ear.  The set up ran my 147gr plated and polymer coated weak ass subsonic reloads like a charm.  Overall I could not be happier.  I have a DI 9mm upper that is the benchmark of smoothness, but requires very specific loads to run.  The CMMG system is better!  I also have a billet PSA Glock 9mm lower that does not have the LRBHO feature and no mag overinsertion stop.  I did have a friendly shooter make a mag stop that fits into the groove where the ejector would normally reside.  Have not tried the setup, but he has one running 100% in his setup.  I have been waiting for just such a system.  Overall, I could whole heartedly recommend CMMG’s product.  I plan to buy the 45acp version this year.  I may just buy the entire gun.  LRBHO is kinda a feature I really value in my PCC’s as I am a competitive shooter.  I fear trying to cobble together a 45acp may not give me the level of reliability I am hunting for in a LRBHO system.  Would love to hear a detailed account of anyone using the system in a Colt pattern mag lower.  I hate having to figure out mag clearance from bolt lugs so if you have experience in running this system in a Colt pattern lower please add in to the conversation.  Want a smooth system like a MP5 but already interested in the AR platform?  Do yourself a favor and buy a BCG/Barrel combo.

Check the Industry forum...

https://www.ar15.com/forums/Industry/9mm-Guard-Barrel-and-BCG-working-with-Colt-mags/145-286362/

I have been running a CMMG Guard Bolt/Barrel combo with colt mags for a few months now. I have a conversion block in my SBR lower. I bought a 16" barrel and had it cut down to 10.5" and threaded 1/2x28. To get it to all run together I had to lower the rails on the feed ramp of the block 0.1 in. and open up the top of the mag slot in my metalform mags by 0.1 in. also. I am running the 3.3 oz. Armaspec Stealth buffer but I had to shim it to keep the bolt in battery or I would get random light strikes. I honestly wish Armaspec made the buffer adjustable weight so I could remove weight and take another ounce or more off of it. The reliability floor for mine at this point is about 120pf ammo. Anything lighter and I don't get a full enough cycle of the bolt to cleanly eject the spent brass.