Reviews & Ratings for CMMG 9mm 5in Barrel Barrel and BCG Kit — 2 reviews — Page 1

Bought this to make a companion upper for my Banshee .45 upper to go with my SBR lower. These are optimized for use with Glock magazines, but they utilize a lower sitting magazine compared to other AR9s. I'm using modified Colt SMG pattern magazines, and have had some feeding issues from the right side of the mag, mostly failures to seat fully due to the case rim catching on the ejector (yes, ejector, not the extractor). Putting a slight radius on the ejector will help prevent this. Single-feed magazines, such as Glock pattern mags, will not have this issue.

It's good to note that the radial-delayed blowback mechanism uses a STANDARD WEIGHT carbine buffer and buffer spring. Do not use a heavy buffer with this setup or it won't run properly.

Recoil is VERY light and slow, which is WAY different compared to a straight blowback AR9. It's a lot easier on your triggers as well, so you don't need a dedicated fire control group; a standard AR15 trigger group will work, including match drop in triggers.

From what I've noticed, it makes for a great suppressor host. The radial delayed blowback is pretty quiet, especially with subs. Very little to no port pop and no gas in the face.

Took my fresh 9mm pistol build out this weekend to test function. I upgraded from a blowback operated system to the CMMG system in hopes of a lighter, less jumpy and controllable gun for my wife. Unsure of what to use for a spring and buffer, I tried a standard carbine buffer and the heavier spring that I used on previous blowback setup. The spring was too heavy and would not allow the bolt to travel far enough back to engage the last round bolt hold open. I swapped the spring and buffer for a JP enterprises Carbineweight captured spring system. It ran flawlessly after that. There was also a noticable difference in recoil compared to the blowback operated system I was running before. Great product so far.