I want to build an AR22 pistol on the cheap, using a BCA 10.5" dedicated upper and a PSA pistol lower, a cheap hinge and either just a buffer tube or a lightweight brace.  I'm having a hard time finding the hinge and lightweight brace that's cheap.  Any suggestions?

I used one from Aliexpress. It's airsoft, but so is 22lr.

You do know you don't need an extension (buffer tube) for a dedicated 22lr carrier, right? Just making sure.
I did mine on an SBR so the stock was needed. Seems like a lot of work for no reward (brace?).

A KNS 1913 end plate and SB 1913 brace works wonderfully. Not cheap, but I have seen some good deals on the EE recently. The polymer on is a tad longer than the aluminum one and works perfectly on an AR-22 pistol (cheaper, too). Folds to the left so doesn't interfere with ejection port. Only possible disadvantage is that it won't fold flat with a 50 rd. drum in.

Would like to hear more about this.  I have an AR 22 and would consider a folding brace or, depending on the final ATF rule, a folding stock. Is there a plug of some sort to hold the carrier in place so that the spring and buffer can be eliminated?

@Piratepast40
You don't need anything for dedicated 22lr. The carrier rides inside the bottom of the charging handle and can't move rearward (out of the receiver).
I'll try to remember and post pics of what I did.


This is the version I bought. Yu don't need the plug, that's for real deal 5.56.
I cut a cheapo extension down and used something like this for the shoulder pad. Slipped a buffer tube foam over the tube.

Here is the KNS one: https://www.knsprecisioninc.com/product/ar-mcx-stock-adapter-with-flange/

Here is the BoreBuddy one: https://borebuddy.com/product/22ar-folding-stock-adapter/

I went with the KNS one as it came with a 1913 rail already.

Did this to both of mine

I used this UTG folding hinge on a Ruger Charger in a PMACA chassis to connect a KAK 81/2" buffer tube... since there is no recoil system passing through, it is just a hinge... it came from S&P Outfitters   IIRC about $12

https://www.youtube.com/watch?v=DT97ANKgENg

Yep, already know.  But with such a long barrel the tube or brace will give me something to rest my cheek on.

Yes, the pressure is concentrated against the threaded upper part of the lower.  Based on what Bore Buddy said about the pressure plug, the plug transfers the force across the rear face of the bolt so there is no longer single point stress on the lower.  Is it marketing hype?  I don't know.  Are AR-22 lower conversions prone to damage or failure in this way?  Anyone else hear this or am I the only one worrying unnecessarily?

The pressure plug just puts a little pressure on the BCG, there's perhaps a 64th or less amount of play if you don't use it. They generally work just fine w/o it. With just a backplate, there's a (very) little play. In the pistol with which I'm familiar it makes no difference (runs great, eats most anything). One can make a thin gasket or use a dap of silicon on the backplate to eliminate the play if one wants.

I'll have to look at BBs site again, I don't recall seeing anything about stress. The .22 BCG is self-contained, I don't believe it's possible for it to ever stress a lower.

The unconstrained bolt group does impact the lower above the threads and will wear the anodizing away on that area.  The BoreBuddy folding stock adapter can be adjusted in and out to take all the play out of the 22lr BCG, avoiding the impact to the lower.  If you have a cheap lower and don't care, it's not the end of the world to lose the ano, but if you have a nice lower, you can avoid the finish damage.

If marring the finish is the only concern, then my respect for Bore Buddy just went into the toilet.  Frankly, I can no longer trust them to be telling the truth about any of their products if they decided to lie about the pressure plugs.

Here's mine





I bought this back around 2006. It has, easily, over 20k rounds through it. I put >4k rounds through it, just last year. Here's where the back of the carrier rides (I just took pic today).



Bore Buddy''s claim makes sense, from a physics standpoint, but my firearm is evidence that not everyone needs a plug.

I really like your setup, it's almost exactly what I'm thinking... but...  is this a legal pistol brace or would I have to get a permit for a SBR?

I have a BCA dedicated 16" .22lr upper.  Although it's not a CMMG, looking at the photos it looks similar.  BCA claims that a buffer and spring aren't required in order for the upper to work.  When I cycle the bolt manually there's a small gap between where the BCG rests and where the buffer begins.  If I continue to pull back on the bolt I can feel where the BCG engages the buffer.  I've had no cycling issues with this upper and I'm wondering if I may once I replace the buffer with a plug for the hinge.

Mine is an SBR.
The buffer and spring are irrelevant. Here's why.

Shotgun your rifle, put your finger on the back of the carrier, and push it forward. Now, look where the back of the carrier ends, in relation to the rear of the upper. Mine is a bit proud of the receiver, maybe .002in. The back of the carrier should be a circle with a little rectangle on top, near the charging handle. That little bit is what's going to hit the inside face of the buffer tower.

When closed, I can just slide a .003 feeler gauge through. So, my carrier can move rearward only .003in. However, the top portion of the carrier, which contains the spring, is inside the channel of the charging handle. It's in their firmly and has zero play.

I'm not familiar with the kit you want to use or if the plug is even needed (I didn't install the one that came with mine). If it's necessary and in the way, I'm sure a couple seconds on a belt sander will square it away.

Bore Buddy didn't invent the pressure plug, but they did improve it.

Most people now have dedicated 22lr uppers, but if you go back a few years, the market was smaller and had a lot of people using a conversion chamber insert that could not lock into or onto the barrel.  For those users, I think the Plug may have helped keep everything forward; there were lots of posts about taping some coins to the face of the buffer to press on the back of the carrier as a cure for light strikes.  When a chamber insert or collar is pulled backward, the falling hammer wasn't just hitting a firing pin, but was also relocating a chamber insert.

I have never used anyone's Plug, but I also have no conversion units.  I also don't have the thing that rests in a Charge Handle that keeps brass out of it because I don't need it.  I do need some of the parts BB makes, so I just buy those.

I can't tell you who to trust or respect, but if you need a bolt weight, heavy duty extractor spring or durable firing pin, I don't know another vendor from whom you could meet those needs.

The significant 22lr AR parts vendors I've dealth with are ARCatch22, Redi Mag (They make the BMA), and Bore Buddy.  For core parts I've dealt with RTB as well as CMMG.

My experience with all of them is that they are forthright and supportive vendors.  My two cents.

Navy, if you were to glue a piece of silicone or polymer to the rear face of your BCA BCG right at the top where it is square so that it would just engage the top of the lower, would that small gap disappear?

ETA - where BCA controls the dimensions of the barrel tenon and the length of BCG and the specs of the upper receiver, I can't think of a good reason for them to provide an upper with a too short BCG.

Most people use the insert or the dedicated solid CH to prevent gas blowback.  I never needed one for function, just nice to have less gas in the face, and that's exactly what it does for me.