Several customers have been inquiring about 9mm AR's lately. After looking into the topic, it is evident great strides have been made in this format in recent years, completely unbeknownst to me! So, I figured it was time to jump in and build one.
The issue I have with 9mm AR's those using UZI/Colt magazines is last century I had a lot of issues with them. They're brutal to load, for one thing. And drop one and see what happens!
The Glock magazine variants work fine, apparently, but to me it just looks so wrong.
So, I was happy to see that Quarter Circle 10 is building BILLET(!!!) AR' receivers that will accept the second best sub-gun mag in the world, that for the MP-5. (The best magazine is I think the Sterling.)
It gets better: QC10 also makes outstanding barrel and bolt assemblies for the 9mm AR' application.
So here's where I am so far, with my first such project. Besides the previously mentioned QC10 components, I'm using a V Seven receiver end plate and tube nut plus safety selector, Seekins oversize bolt release, and BAD steel push pins. This will be my first use of a Vltor A5 recoil system on an AR' pistol format. I like it because it' uses a rifle recoil spring, much more reliable and long lasting than a carbine recoil spring - and the tube is about 3/4" longer than a carbine tube. I went with the A5-H4 buffer, their heaviest, for suppressed use. That's a Surefire Ryder 9 Ti can stuffed inside the BCM KMR.
I started out with a LaRue MBT trigger, my favorite for 90% of AR' applications, but it became apparent rather quickly that it was not compatible with the ramp on the underside of the QC10 bolt carrier. So, I switched to a Geissele SSA with a conventionally shaped hammer.
The Gear Head Tailhook may be the most clever arm brace to be designed to date. It has a push button, spring loaded latch, making it easy to deploy.
The MP-5 magazine seats positively and drops free with zero hesitation. The bolt catch does not hold the bolt open on the last shot, as with an AR', but it does work in the manual mode perfectly.
