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.22LR AR Pistol Build

2/21/18 - One of the joys in life is shooting .22 LR weapons. Cheap and fun, I'd reckon that most of us started shooting with some sort of .22 LR when we were young. Here's one I put together for my son to shoot.

Background - When I first started shooting, it was with an AMT Lightning, a stainless steel clone of the popular Ruger 10/22 (the rifle which most kids I knew had). When I recently started my 10-year old son shooting, I started him off with airsoft guns, then moved onto an air pistol, then .22 LR pistols. I then introduced him to the .22LR AR rifle that I had. It's a full-size rifle, and rather long and heavy for him. He can shoot the rifle supported, but had trouble shooting it offhand, so I decided to reconfigure one of my AR pistols into a 22 LR AR pistol for him to use, which would be more in proportion to his smaller stature. For this build, I used a combination of parts I already had on hand, and some new ones. My goal was to put together something short and light weight, that would be a good weapon to learn on.

The Upper - Here's a list of components I used for the upper:

As my son is a lefty like I am, a pistol caliber shell deflector helps keep the empty cases away from the face. The shell deflector that I ordered from CMMG is different that the one I have on my .22LR rifle upper; which looks like the old Colt 9mm upper shell deflector. Also included in the kit is a shortened ejection port cover. BCM's receiver is machined from 7075 T6 forgings and comes with laser T-markings and M4 feed ramps (irrelevant in this case).

My son has small hands, so a slim and light handguard was necessary. I chose the BCM MCMR. The MCMR is BCM's M-LOK compatible version of their popular KMR Keymod handguard. The only difference between them is the mounting interface. The MCMR is available in 7", 8", 9" (shown here), 10", 13" and 15" lengths, which should meet most users needs. I chose the 9" version to go with the 9" barrel, knowing that the handguard would be longer than the barrel by about 1.5". While the 8" handguard will have resulted in a shorter overall length, I'm not fond of the ultra short 'kitty kat' AR uppers, and wanted this pistol to have a more balanced look and usable handguard. The handguard came with an M-LOK compatible sling mount and rail (for a limited time only). Included in the package are all necessary mounting hardware, thread locker, and wrenches.

The BCM rail panels and KAG were the obvious choices to complete the handguard. The rail panels are compact and provide a grippy surface, and the KAG works well as a hand stop/index to ensure that my son's grip stays consistent. The rail panels are ultra low profile, which are perfect for small hands.

The CMMG 22ARC bolt group kit is really nice. The only modification I made was to break any sharp edges on the chamber entrance of the barrel with a dremel, and polish the feed ramp. The CMMG feed ramp looked great right out of the box and I was very impressed with the quality of the 22ARC bolt group compared to my old Spike's Tactical .22 LR. Note that they are not compatible with each other. The CMMG ARC barrel collar assembly will not fit on my Spike's Tactical .22LR barrel and vice versa.

BCM receiver

With CMMG shell deflector

CMMG Barrel and bolt group


Rail panel kit and KAG

Rail and sling socket included with MCMR

The MCMR installs exactly like the KMR. For details and pics, please read my previous detailed write up on the KMR. Installation is a breeze, and a great plus about the installation wrench is that it doubles as a receiver extension castle nut wrench.

Compared to 15" KMR

Barrel assembled to upper

Handguard attached

For optics, I took my Larue Irondot off another upper I had as it's compact and light weight. It has the same Burris FastFire that's been mounted on it for over 10 years and it's still working well. For back up sights, which are actually there to teach my son how to use iron sights, I asked for a set of PTS EP BUIS from a friend. PTS is an airsoft company that used to manufacture the Magpul PTS line of products. Ever since Magpul and PTS parted ways, PTS has introduced their own products, which also include items that fit on both airsoft and real weapons. While they state that all their products are for airsoft, training and simluation purposes only, some of their products like their stocks and grips are fine for use on range guns. The PTS EP BUIS set are made of Dupont Zytel reinforced polymer and are small and light weight. Since this is a .22 LR pistol built purely as a range gun, I didn't see the need to put aluminum sights on it and had no qualms about putting PTS sights on it. The PTS sights are easy to adjust without tools and function well for their intended purpose. I don't think I'd put them on a serious 5.56 upper though.

The SA Accubrake is something I've had in my parts box for over 20 years, maybe more. I can't really find any info on it anymore, but it was marketed as a 'tunable' brake which could be adjusted and locked in place. The Browning BOSS system does the same thing; it tunes the vibrations of the barrel by lengthening or shortening it. That's irrelevant for this pistol build, but it looked cool, was the right length, and wasn't being used so I installed it on the end of the barrel.


Rear view

Sight picture

Complete upper

Lower Receiver - I had a lower that was already assembled into a 5.56 pistol, so decided to use it for this .22 build with some minor component changes.

Here's a list of components I used for the lower:

I've built a couple of AR pistols, and both of them sport LAW Tactical folding mechanisms with braces. Those, however, are too long for my kid, who is small for his age, so I re-configured one for this purpose. Rather than going with the Phase 5 Hex tube I had on hand, I thought that the SB Tactical SOB brace would not only look better, but provide a more comfortable cheek weld. One reason I don't like foam covered pistol tubes is that the foam collects dirt, dust, facial oil, sweat and skin over time. Gross. A bare tube isn't that comfortable, so a brace is the best option in my opinion. The BCM Pistol receiver extension has a 1.2" diameter and is machined from 7075 T6. It's compatible with most pistol braces, and carbine buffer and action springs. Since the pistol tube is a larger diameter than a standard carbine receiver extension, some castle nut wrenches won't fit, like the Hammerhead. It's just as well that I got the MCMR because the installation wrench can be used to tighten the castle nut on the pistol tube.

The FCD EMR-A features an extended paddle so my son's short fingers can reach it for mag changes. He's a lefty like me, and cannot reach a Norgon Ambi-catch. The pistol grip is from the aforementioned PTS company, and has worked well on a couple of others rifles of mine. While marketed for airsoft, the grip is made of Dupont Zytel high performance reinforced polymer, and I'd trust it just as much as many of the grips made for 'real' guns.

Battle Arms Development's BAD-ASS ambi safety was the logical choice for this build. I used the standard lever on the right side (I usually use a short one) for my son's smaller hands. Since this 80% lower was devoid of selector markings, I drilled dimples under the safety levers and filled them with red paint so that a red dot is visible when the selector levers are rotated to 'Fire'.

BCM's PNT trigger assembly (Polished - Nickel - Teflon) are an enhanced mil-spec fire control assembly and bridge the gap between a USGI trigger and a specialty, target trigger. The PNT retains the reliability of a mil-spec set up while reducing the creep and grittiness present in the standard trigger setup. I've used my .22LR AR rifle upper on various lowers, and have noticed that I'd have issues with light strikes when using lighter triggers. Sometimes I'd remove the round, rotate it, and put it back in the chamber and it'd fire. Ever since I went back to heavier triggers on dedicated .22LR lowers, the reliability increased with less failures to fire.

The SBT SOB pistol brace slides onto the BCM Pistol receiver extension snugly, and is quite solid on it. It would rotate slightly, but not that easily. However, to eliminate all rotation, I used a bit of double-sided adhesive tape on the tube, then slid the brace over it. It didn't rotate after that.

BCM pistol tube

Pistol tubes

Using MCMR wrench for castle nut instllation

Red dot 'Fire' indicator

SOB pistol brace

Notes/Observations - Fully assembled, the pistol weighs 5 lbs on the dot; which my son is able to handle quite comfortably. It's definitely more in proportion to him now and is very well-balanced. With my rifle, he looked like he was trying to shoot a musket. I used a laser boresighter to sight it in before taking it to the range, and it didn't require any adjustments. At 50 feet (approx 17 yards), the pistol shot 2" groups offhand, so it was good to go in my book for my son. I did not shoot it from a rest, and I'd expect it to shoot tighter groups when supported.

Fully assembled

Trust me; he's smiling
At the range

Shooting the Walther P22

I used Black Dog Machine 10-round magazines for my son to practice reloads and other drills I'm starting him on. We went through 200 rounds of CCI Mini Mags and 150 American Eagle HV Plated ammo. To my pleasant surprise, we did not have a single misfeed or failure to fire; or failure to extract. Typically when shooting .22 LR, I'm kind of expecting a few duds or bullet noses catching on the chamber edge, but nothing of that sort this time.

As for size, the AR pistol was perfect for my son. My 10/22 is in a target stock and is too long/heavy for him, as is my .22LR AR rifle. When teaching a kid to shoot offhand, I think that it's important to ensure that the weapon is proportional in size to the kid; otherwise it can be more challenging than it needs to be, and not as much fun for the kid. I know that there are kid-sized rifles like the Crickett or other single-shot rifles. I don't really think that it's necessary to start with a bolt-action. When I first started my son on my .22 AR, I had him load one round per magazine until he graduated to two. With the AR pistol, I had him load 2 rounds per magazine so he could practice some reloading drills. I was very proud of him; he handled it like a boss; and wasn't struggling with its length or weight at all. The AR .22 pistol is a perfect companion to my Walther P22, which also fits his small hands.

The other good thing about the .22 AR pistol is that it's not too small for me to shoot, unlike some of the youth-sized guns; plus it can be fired at indoor ranges that don't allow rifle calibers. It's still my pistol, after all - he just gets to shoot it. Building an AR is always fun; but this time it was all the more enjoyable to share the process with my kid.








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