What is everyone using for stock adapters for their 22LR AR builds?  I would like something that adapters the AR stock adapter to a Picatinny style stock adapter.

I am worried about fitment so that the BCG doesnt bounce around in the lower.

There's a few. Strike Industries, Rehv Arms, KNS, Midwest Industries. KNS is probly the oldest and most popular if the bunch.

I have the Rehv and KNS. Rehv is good if you want ultra lightweight, but KNS has more stock attachment areas.

BoreBuddy has one specifically for the AR22 as well.

What stock adaptor?

I use the KNS adapter with flange, plus a 2mm silicone bumper on the inside to add a tiny bit of tension to the .22 bolt group. Malfunctions have been essentially zero since adding that.

Did you get this silicone pad or did you just use some caulk to create the fitment?

It’s a silicone bumper used for hanging photos. I think I paid $5 for 300 on Amazon for using with my photo prints.

What he said...

Nice setup!


Attached File

Mini AR pistols have their own cult following.

Everyone posting pics of their ~4.5" bbl, has it been reliably cycling?

Just ordered a 4.5" CMMG and hoping I made the right choice over the 9".  Will be suppressed most of the time.

Yep, they cycle.

Mine cycles just fine.
It's a fun plinker.  



I've become a fan of CMMG's products as their designs are well thought out.

My 4.5" build cycled fine with standard velocity ammo until I added a Bore Buddy bolt weight. With the bolt weight, it will only cycle reliably with high velocity ammo. But that is okay since I like the benefits of using the bolt weight. It definitely helps with bolt bounce and as an added bonus, the inside of the pistol stays cleaner too. Mine is quite accurate too. I can make good hits on 4" clay birds out to 85 yards with it. I do use a sling with mine along with a red dot sight. I push out against the sling for a more stable platform.

My 4.5” has not missed a beat over about 300 rounds with a half dozen std to hi-v loads, RN, FN, and several varieties of HP.   Subs feed and eject perfectly but won’t cock the hammer.

Whether any particular AR .22 upper, be it a dedicated upper assembly or conversion assembly installed in a 5.56/.223 upper, will function reliably with any particular .22 ammo, be it standard velocity, high velocity, subsonic, etc., depends on a number of factors.  The following are things that come to mind and so the list should not be consider all inclusive.
For the upper: barrel length; suppressed or not suppressed, and if suppressed, the amount of boost provided by the silencer; degree of chamfer (‘throating’) to the lower lip of the chamber; correctness/completeness of seating the barrel into the upper; and tolerances of manufacture of the upper and barrel vis a vis each other.
For the .22 bolt/recoil assembly: recoil spring rate (too high and too low); degree of roughness on the interfacing surfaces including how well the firing pin and extractor move in their channels; total reciprocating weight (too high and too low); tolerances of manufacture of the components vis a vis the barrel, the upper receiver, and the lower receiver; mag spring force and mag lip drag caused by the mag or the bolt.
For the firearm: tolerances of manufacture of the components including the lower receiver; hammer, trigger, and disconnector spring rates; hammer mass; and degree of roughness on the interfacing surfaces.  When used in connection with a closed bolt full auto firearm (e.g., M16), the forward momentum required to trip the auto sear.
For the ammo: ammo power factor taking the barrel length and suppression effects, if any, into account; ammo coating (e.g., dry wax, oily wax, copper wash, etc.); projectile shape (e.g., round nose, truncated, hollow point, etc.); and casing thickness, particularly in the rim.
Best of luck.
MHO, YMMV, etc.  Be well.