FYI CMMG 22lr Bolt and Folding Adapters

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Kit
Posts: 17
Joined: Tue Jun 15, 2021 1:03 am

FYI CMMG 22lr Bolt and Folding Adapters

Post by Kit »

I've been running a system for this that is a little different than you'll find anywhere out there and thought maybe this information could be useful to others so here it is.

This is in regards to use of the pressure plug in combination with folding adapters.

I use the BoreBuddy pressure plug with Sylvan folding adapters and the CMMG 22lr bolt and it does a great job of keeping great forward pressure on the 22lr bolt. You have to be a little creative in your thinking though. It's the same basic process as normal however with 2 parts in specific configurations.

The pressure plug goes inside the buffer tube the same as it always does however the open end of the plug has to face forward. Next you close the folding adapter. Next you insert the bolt extension piece, the part with the rubber "O" rings that normally goes inside the BCG, backwards ("O" ring end first) through the adapter area to the pressure plug and it so happens that it fits nicely inside the pressure plug's open end. You can feel it when the "O" rings pop inside the open end of the pressure plug, almost like it was made to do so. The metal end of the bolt extension part does extend about 3/16" too far from the buffer tube / folding adapter area however this is what helps to create the forward pressure force on the 22lr bolt. Carefully push the bolt extension piece rearward against the buffer spring while at the same time closing the upper down so that the non "O" ring end of the bolt extension piece comes to rest against the rear metal plate of the 22lr bolt, an old credit card and a little oil makes the process easy.

The forward pressure is great. I don't use any other weighted parts on the bolt itself, there are zero other bolt/buffer modifications, and there is zero bolt bounce. I have 2 of the CMMG 22lr bolts and I've done this in barrel lengths 7.5, 10.5, 13.7, 14.5, and 16 as well as in systems with PDW short buffer tubes, regular buffers springs, flat buffer springs, and the Geissele Super 42 buffer system and I have never had a single mis-feed or jam using any of the CCi ammo including their 45 grain suppressor line, any of the Winchester Super X stuff, the Federal Auto-Match LRN, and several types of HV Aguila....not 1 single mis-feed in thousands of rounds. In my experience the most important things to making the 22lr conversion bolt run flawlessly are good forward pressure on the bolt, quality 22 ammo, use of oil on the bolt (spring, tracks, moving parts), and cleaning the bolt between uses.

Hope this helps....$0.05 to $0.20 is one heck of a lot better than $0.50 to $1.00 per round. Good Luck!
BoreBuddy
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Re: FYI CMMG 22lr Bolt and Folding Adapters

Post by BoreBuddy »

Great writeup -- the piece fitting into the hollow end of the plug is just luck, not a design feature as much as I'd like to take credit for it!

I'll have to go try out the law folder to see if the same thing can be done.
HDCharlie
Posts: 7
Joined: Sun Sep 26, 2021 2:06 am

Re: FYI CMMG 22lr Bolt and Folding Adapters

Post by HDCharlie »

There is another folding adapter available from Matador Arms that has different attributes. This adapter is not made for an AR because it has no way to use a buffer, buffer spring, or a movable bcg. It threads into the back of an AR lower, but that portion of the unit is solid. So, if you're going to build a dedicated .22 lower using CMMG style components, this adapter is an option with several advantages.

One thing that might turn some persons away is the fact that the adapter cannot be tightened to the lower and end up timed right. I used some Loctite to mount the unit to my lower and it works perfectly, with only the slightest gap(.015"-.020"), which is hardly noticeable.I'm sure some of you know this already, but I discovered that Loctite will not cure on anodized aluminum without using Loctite primer. There was a small gap between the CMMG bcg and the adapter that I filled with a small piece of hard rubber that could be affixed to the adapter or just left loose, like I did.

I really like this adapter because I don't have to run an AR buffer or spring in whatever buffer tube I utilize. That would make for an even lighter AR22 if you wanted to use a polymer receiver set.

I tried to post a description of this adapter last evening, but it appears to not have gone through. This is a second attempt.
Kit
Posts: 17
Joined: Tue Jun 15, 2021 1:03 am

Re: FYI CMMG 22lr Bolt and Folding Adapters

Post by Kit »

I'd be interested to know if the system I described, or something similar, works with the Law folding adapter. I chose Sylvan purely on a cost basis and it's worked well however it's a little bulkier than the Law unit. I had originally planned to build a dedicated 22lr using the CMMG conversion bolt, a 5.56 barrel, and the CMMG buffer plug that sounds very similar to the other system described. I was going to go for the CMMG blaster look. I ordered the buffer plug from CMMG, put the gas block on backwards to plug the gas port, and proceeded with the build. About half way through the project the fact I was reducing overall potential function started bugging me in a way I couldn't shake so I back tracked, cancelled the plug order, fixed the gas system and ended up with a little AR15 that's very obnoxious using 223/556 and really fun to also shoot 22 through.
HDCharlie
Posts: 7
Joined: Sun Sep 26, 2021 2:06 am

Re: FYI CMMG 22lr Bolt and Folding Adapters

Post by HDCharlie »

The Law should work since it is what the Sylvan was copied from and they function the same way, I have used a Law on an AR9 and a Sylvan on an AR15. Other than one is made from aluminum and the other from steel and the different method of tightening them to the lower, they are basically the same. You get the same result at different price points.

There is another adapter that can be used by someone building a dedicated AR22. It is made by UTG and costs a mere $25. It seems like a Bore Buddy pressure plug might fit in the end that threads into the lower and I'll report back on that later today.
HDCharlie
Posts: 7
Joined: Sun Sep 26, 2021 2:06 am

Re: FYI CMMG 22lr Bolt and Folding Adapters

Post by HDCharlie »

The Bore Buddy pressure plug will not work. The inside diameter of the adapter is too small. I am going to make a plug using a piece of 5/8" diameter Delrin rod and a 1"long 1/4"-28 screw. Will try to post a pic when it's finished.

After working with several different adapters, I've come to the conclusion that the best one overall for this application is the Law. It's expensive, but you get what you pay for. Now, if you're going to have to buy a new lower anyway, the 17 Design with the built-in folder would probably be the most economical way to go,with the least effort and the cleanest finished result.
Kit
Posts: 17
Joined: Tue Jun 15, 2021 1:03 am

Re: FYI CMMG 22lr Bolt and Folding Adapters

Post by Kit »

Good to know. Any chance you could use something to increase the diameter of the plug unit or decrease the space within the plug? Seems like the correct size of rubber like tubing inserted and/or glued into the plug might work.

I definitely recognize the Law adapter as the benchmark unit, that said I found a really good sale on Sylvan adapters at about 1/3 the cost. Having 3 versus 1 for nearly the same price helped me to appreciate the Sylvan units. Have to admit though, I still want a Law at some point.
BoreBuddy
Site Admin
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Re: FYI CMMG 22lr Bolt and Folding Adapters

Post by BoreBuddy »

You could also use our adapter if you are planning on a dedicated 22lr lower:
https://borebuddy.com/product/22ar-fold ... k-adapter/
Kit
Posts: 17
Joined: Tue Jun 15, 2021 1:03 am

Re: FYI CMMG 22lr Bolt and Folding Adapters

Post by Kit »

Appreciated, will keep that in mind.
HDCharlie
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Joined: Sun Sep 26, 2021 2:06 am

Re: FYI CMMG 22lr Bolt and Folding Adapters

Post by HDCharlie »

The UTG adapter I mentioned above will not work. It won't allow the charging handle to operate.
Kit
Posts: 17
Joined: Tue Jun 15, 2021 1:03 am

Re: FYI CMMG 22lr Bolt and Folding Adapters

Post by Kit »

Good to know. If I ever go back to a dedicated 22lr set up project in the AR15 platform without use of a buffer tube, seems the CMMG or the borebuddy screw in plugs in place of the buffer tube are probably the way to go.
HDCharlie
Posts: 7
Joined: Sun Sep 26, 2021 2:06 am

Re: FYI CMMG 22lr Bolt and Folding Adapters

Post by HDCharlie »

I just checked, and the UTG adapter will work with one of my side-charger uppers, but it will only fold to the right. The upper I checked is made by New Frontier Armory, model C-4.
Kit
Posts: 17
Joined: Tue Jun 15, 2021 1:03 am

Re: FYI CMMG 22lr Bolt and Folding Adapters

Post by Kit »

I've never used a side charger on anything. I am starting to warm up to the idea of giving it a try. If for no other reason than to reduce gas in my face.
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