For a few years now, I have wanted to build a 9mm AR that takes Glock magazines. Mainly because the handgun I carry every day is a Glock 19. About a month ago I finally built my 9mm AR and it has been awesome. From the first round down the pipe it has run like a sewing machine with zero failures and the bolt hold open on last round is even working. Since then I have had a ton of questions asking me what specific parts I used in my build so I wanted to put all of the details together in on place for people to see and get information from. Once I have had a chance to put a ton more round through it I will follow up with a review as well.
My build started with Quarter Circle 10. They seem to be leading the pack in innovation regarding pistol caliber AR’s. They offer a Glock Small Frame lower for 9mm, 40SW, 357Sig, a Glock Large Frame lower for 45ACP and 10mm and a Colt 9mm lower as well as bolts and barrels for these as well. I wanted my AR to take the same mags as my Glock 19 so I went with the stripped Glock Small Frame 9mm Lower, 9mm BCG and 9mm 7.5″ barrel. Any AR-15 upper will do but I use a Rainier Arms mil spec forged upper minus forward assist. QC10 will be coming out with their own side charging upper with pistol caliber ejection port soon too. I also used an ALG Defense ACT trigger and need to upgrade to an ambi safety soon.
I covered the barrel with an SLR Rifleworks 8″ Solo Ultra Lite M-LOK rail. SLR rails are becoming one of my personal favorites. With such a short rail I decided to put an Arisaka Defense M-LOK Finger Stop underneath it. Its just small enough to not be in the way but big enough to keep your hand from getting too far forward. You may have noticed already but the QC10 barrels are straight blow back and do not require a Gas Tube or Gas Block.
For the muzzle device I chose the new 9mm Linear Comp from Kaw Valley Precision. I have used KVP’s Linear Comps for 300BLk and 5.56 before and the work great. Now they offer the same product in a 9mm version with a 1/2×28 thread pitch which is what I needed for the QC10 barrel. The fact that my barrel was shorter than my rail made the KVP linear comp a no brainer but it also looks sweet only sticking half way out the rail.
For my optic I chose a Vortex Optics RAZOR 3MOA red dot and mounted it to a Cross Machine Tool red dot sight mount. This is a nice light weight, compact optic setup that I feel has very fast target acquisition.
One item I recently installed was the Law Tactical Gen3 Folding Stock Adapter. At the moment I have this gun set up as an AR Pistol but will be converting it to a registered SBR with a stock soon. I love how compact the folding stock adapter makes this for transport. I can fit it in a small backpack, bag, case, etc without having to separate the upper and lower. It is quickly ready to shoot by flipping the buffer tube straight as you remove it from its concealment.
I was able to remove the extra weight at the rear of the carrier by removing the large roll pin and sliding it out. That is where the carrier extension for the Law Tactical Folding Stock Adapter goes.
The Law Tactical Gen3 Folding Stock Adapter has a lowered hinge to keep it away from your knuckles but just to be sure I am using a Fortis Manufacturing Hammer charging handle which has a really nice sized lever on it. The Hammer is one of my go to charging handles. Great build quality and affordable.
Originally I started out with a standard carbine buffer spring and carbine buffer combo. It worked just fine but the guys at QC10 told me they recommend a heavier buffer, somewhere in the 5-6 ounce range to slow the carrier down a bit. I installed a Damage Industries 5.4 ounce H3 buffer and it continues to run perfect.
Aside from a custom mag release and bolt catch assembly, the QC10 lower takes normal mil spec parts kits. You can see the Bolt Catch itself is mil spec but it is actuated by a pre-installed lever that contacts the magazine follower. This tends to be an issue with some mags as the spring pressure isn’t always strong enough to press the lever up and activate the bolt catch. This can be remedied by installing Wolf High Power springs inside the magazine. I bought a couple of SGM Tactical 33rd magazines from AIM Surplus and they seem to have better springs than the OEM ones. So far they are activating the LRBHO (last round bolt hold open) every time.
So, there you have it. That’s pretty much my build in a nut shell. As I always tell people who are intimidated with building their own AR, “Its easier than you think”. You’ll love the increased range and accuracy you get out of a 9mm AR and being able to carry one type of mags to feed both your Primary and Secondary is awesome. Let me know if you guys have any questions or comments.