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Old 09-09-2019, 09:25 PM
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Question Performance and compatibility questions



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Years ago I was given a Ciener conversion for Rattle Battle practice, and through my DPMS NM barrels it shot reasonably well at 50ft, about 3 MOA.


With that expectation, when requesting gear for a fledgling junior service rifle program in my club, we got 3 centerfire rifles and 3 CMMG conversions. One combo might average 3-4 MOA, but it's otherwise 6-10 MOA crap that's only good for introducing noobs. I need 2 MOA or less to be able to train someone up to Expert/Master class.



Participation is picking up again, so I'm looking at requesting parts for dedicated uppers. The kids are about 5', 120lbs wet and can't handle 10lb HBAR A2s yet, so I'm copying my carbine: https://www.youtube.com/watch?v=S4nJyLN1wnI


The important parts are:

-CMMG dedicated 16" carbine barrel with FSB.

-Dedicated collar to replace the 5.56 chamber adapter on the existing conversions.

-UTG Pro freefloating carbine quad rail.


Completed, the upper is in the $500 range which is easier to ask for than $900+ from Keystone/CLE, etc. But is it most likely capable of 2 MOA?





One of the hurdles when transferring to centerfire is the slight manual-of-arms change. Can the M&P15-22 magazines with ARcatch22 magwell adapter and ARcatch22 bolt catch function in a CMMG system?
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  #2  
Old 09-10-2019, 06:40 AM
zukiphile
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Originally Posted by H-R-B View Post
Years ago I was given a Ciener conversion for Rattle Battle practice, and through my DPMS NM barrels it shot reasonably well at 50ft, about 3 MOA.
A half inch at 50 feet is better than I would have expected from a conversion.

Quote:
Originally Posted by H-R-B View Post
Completed, the upper is in the $500 range which is easier to ask for than $900+ from Keystone/CLE, etc. But is it most likely capable of 2 MOA?
Mine will print an inch at 50 yards, but to stay under two inches at 100 yards, I would use a heavy taper barrel.

Quote:
Originally Posted by H-R-B View Post
One of the hurdles when transferring to centerfire is the slight manual-of-arms change. Can the M&P15-22 magazines with ARcatch22 magwell adapter and ARcatch22 bolt catch function in a CMMG system?
Yes. For use in three position, I would omit the bolt catch detent and spring entirely.

https://www.rimfirecentral.com/forum....php?t=1134191

Last edited by zukiphile; 09-10-2019 at 08:46 AM.
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Old 09-11-2019, 12:10 AM
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Originally Posted by zukiphile View Post
A half inch at 50 feet is better than I would have expected from a conversion.

Mine will print an inch at 50 yards, but to stay under two inches at 100 yards, I would use a heavy taper barrel.

Yes. For use in three position, I would omit the bolt catch detent and spring entirely.

https://www.rimfirecentral.com/forum....php?t=1134191

-It was a surprise. I thought everyone else with conversions just couldn't shoot, but it was luck o'the draw.


-Sounds sufficient.


-Just for reliable catching and/or ease of releasing?

Last edited by H-R-B; 09-11-2019 at 12:12 AM.
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Old 09-11-2019, 06:16 AM
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Originally Posted by H-R-B View Post

-Just for reliable catching and/or ease of releasing?
Reliability in the magazine operating the catch. The bolt catch spring and magazine spring push in opposite directions. Since the rifle is always held right side up in three position and the bolt catch will operate just by gravity, it doesn't make sense to incorporate a bolt catch spring the purpose of which is to make the catch work even if the rifle is upside down.

Yes, I've put one together this way and it works better. If you really want a bolt catch spring, the ARCatch22 people sell a reduced power spring.

Last edited by zukiphile; 09-11-2019 at 06:30 AM.
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Old 09-11-2019, 07:30 AM
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Quote:
Originally Posted by H-R-B View Post
The important parts are:

-CMMG dedicated 16" carbine barrel with FSB.

-Dedicated collar to replace the 5.56 chamber adapter on the existing conversions.

-UTG Pro freefloating carbine quad rail.
I wouldn't tell you how to build your rifles, but if low cost, light weight and accuracy are your goals, those bolded components aren't optimal.

The CMMG carbine barrel with FSB has an awfully short sight radius and is a bit pricey unless your goal is to have something that looks like an M4.

Quad rails aren't light, or comfortable for most people. A heavy taper barrel, and a 12 to 13.5 inch free float tube would weight about the same, cost a little less and would have you at less than 2moa at 100.
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Old 09-11-2019, 08:15 AM
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CMP service rifle trainer for small folk. I'm more of a purist amongst gamer guns, so I like the FSB.
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Old 09-11-2019, 12:35 PM
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If your wanting a fully functional bolt catch with an AR-15 in 22 LR Boonie Packer sells a better mag adapter. The BMA permits the use of S&W 15-22 mags which get good reviews.

Right to Bear has jumped into the AR-15 in 22 LR and are selling CMMG compatible barrels and collars for good prices. If your serious about building a couple of these training rifles I would reach out to RTB. Some the rimfire products are out of stock according to the Right To Bear website. If RTB knows what your doing they might be able to accommodate your project with the needed parts.

RGuns and DEZ Tactical Arms sell a fixed A-2 fixed front site gas block assembly which is retained by four Allen screws instead of taper pins. I used one of these front sights on a M-4 build. I used Loctite and it has held solid for many years.

I’d also order a couple of LaRue Tactical MBT 2S triggers which are $87 and would make a great trigger for a 22 training rifle.

A flat top AR-15 in 22 rimfire is a very versatile rifle and I have taught many people to shoot with my AR-15’s with 22 conversion or dedicated 22 LR AR-15.

https://www.righttobear.com/22LR-par...ies-s/1873.htm

https://rguns.net/shop/r-guns-a-fram...ght-750-black/

https://www.shop.deztacticalarms.com...EZ-1035-GB.htm


https://www.brownells.com/rifle-part...prod56474.aspx

Last edited by VASCAR2; 09-11-2019 at 12:38 PM.
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Old 09-11-2019, 01:38 PM
zukiphile
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Quote:
Originally Posted by VASCAR2 View Post
Iíd also order a couple of LaRue Tactical MBT 2S triggers which are $87 and would make a great trigger for a 22 training rifle.]
I've made this recommendation in the past not because I'm enamoured with LaRue's light first stage and heavy second stage, but because of the likely durability of their hammers.

I like Rock River triggers better, but I've also read complaints about their durability.

How many 22lr rounds would you estimate you have on your Rock River?
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Old 09-11-2019, 02:08 PM
VASCAR2
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I have no way of knowing because Iím still using three RRA NM triggers in AR-15 lowers with dedicated 22 LR uppers. My most used upper I shot a minimum of 500-1000 rounds of 22 every month for about ten years. My other CMMG upper probably has 5000 rounds or more and my KKF upper probably has 5000-10,000 rounds through it.

I had one RRA NM trigger go bad but it didnít have but a very few thousand rounds in it. I think that trigger group was just out of spec or defective. RRA will not warranty their triggers with rimfires and the reason I recommend LaRue MBT 2S for $87. I have three of the MBT 2S in centerfire ARís and I like them.

I replaced the defective RRA NM with a Geissele G2S which I like but it is comparable to the LaRue but more expensive.
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Old 09-11-2019, 02:24 PM
zukiphile
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Quote:
Originally Posted by VASCAR2 View Post
I have no way of knowing because I’m still using three RRA NM triggers in AR-15 lowers with dedicated 22 LR uppers. My most used upper I shot a minimum of 500-1000 rounds of 22 every month for about ten years. My other CMMG upper probably has 5000 rounds or more and my KKF upper probably has 5000-10,000 rounds through it.
That's a pretty good recommendation.

Quote:
Originally Posted by VASCAR2 View Post

I had one RRA NM trigger go bad but it didn’t have but a very few thousand rounds in it.
I had one go from semi-auto to very bad in just a couple hundred rounds, but I had very finely tuned it in a centerfire, so I can't really blame Rock River.

Too bad. A finely tuned RR is a nice trigger.

Last edited by zukiphile; 09-11-2019 at 02:56 PM.
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