Project Appleseed

Does anyone have any experience with the CMMG .22 LR conversion kits for AR's?

Yes. A friend and I ran both conversion kits and straight CMMG 22lr uppers.
Both ran great. The straight upper was best for convenience. 

Quote from: cowtipper on February 21, 2020, 08:56:52 AM
Does anyone have any experience with the CMMG .22 LR conversion kits for AR's?

I have seen participants use them at more than a few Appleseed events, and they do function well. 

Most of the conversion kits I have become aware of on the line came to my attention due to good shooter technique and form, combined with excessive group size.

Your experience may be different.

Quote from: cowtipper on February 21, 2020, 08:56:52 AM
Does anyone have any experience with the CMMG .22 LR conversion kits for AR's?

I have seen participants use them at more than a few Appleseed events, and they do function well. 

Most of the conversion kits I have become aware of on the line came to my attention due to good shooter technique and form, combined with excessive group size.

The dedicated 22LR uppers (barrel and chamber in 22 LR) on the other hand are capable of producing very nice group sizes.

Your experience may be different.

I haven't seen very good results with conversion kits in general.  The rifles begin malfunctioning fairly quickly, and my shooters have had to switch to a backup gun or take a loaner.  I've seen armorers report bad results from 22LR soft lead rounds going through an AR-15 barrel, and that soft lead buildup starts plugging up the gas port over the course of thousands of rounds.  An AR-15 barrel needs to fire jacketed rounds to avoid this gas port problem.  Soft lead .22LR needs to operate based on a blowback design with a fully sealed barrel.  It won't work that well on a direct impingement design.  My suggestion is to get a rifle designed from the ground up to be a 22LR rifle.  The conversion kits do not appear to work that well. 

My experiences come on the line and as a user.

We have folks that come to the line with the conversion kits and struggle with reliability and accuracy for sure. Reliability-wise, it is usually because they haven't tested their rifle thoroughly with the ammo they are using or with the upper they have installed it in. Or are just cocky because they think their AR is the greatest but aren't as proficient with it as they think from bench firing.

They also struggle with the right amount of lubrication and cleaning to keep it running. They, like many rimfires, eventually choke out without cleaning - I think it is faster than other 22s, but don't have specific data. The leading and powder clogging can be an issue after thousands of rounds of 22LR in a row - so I put back in my normal BCG after a few hundred and blow it all out in addition to a more regular cleaning and lube schedule. The mags are ok but can also get clogged up and slow if not cleaned a bit.

Accuracy is impacted by a few factors - an inappropriate barrel twist for stabilizing 22LR (most 22s are 1:16, I mistakenly said 1:14 earlier) while many ARs are 1:7 to 1:9) and poor ammunition choices. Running a dedicated upper/barrel works pretty well (though I think the Tippmann is a better choice). Or you can use it with a "retro" barrel optimized for 55gr 5.56mm (1:12). That is what I use mine in for a sometimes loaner and practice rifle: https://www.mdshooters.com/showthread.php?t=235076

5.56x45 bullet is .224 in diameter.

22 LR is .221 in diameter.  Expect 6 Minutes of Angle at best from a conversion kit.  The bullet bounces down the barrel like a musket ball.

I doubt you mileage varies that much from others experience.

Quote from: Charles McKinley on February 21, 2020, 02:19:35 PM
5.56x45 bullet is .224 in diameter.

22 LR is .221 in diameter.  Expect 6 Minutes of Angle at best from a conversion kit.  The bullet bounces down the barrel like a musket ball.

I doubt you mileage varies that much from others experience.

6 MOA is the best I could get with a Ceiner kit (which the CMMG is a copy of).  That was in a Bushmaster 1:9 A2.  I've not seen anyone do better but there are some reviews where guys have done better online.

In a Daniel Defense 1:7 it shot a stellar 30 MOA group!

I'm converting my conversion bolt into a dedicated .22 upper for real accuracy and practice. 

I had the opportunity to use a CMMG dedicated upper .22 cal. several years ago, during the break-in period. In the beginning the upper was firing around 6 MOA, at about 300 rounds through the barrel the group size decreased to around 2 MOA. The upper belonged to OLAdcock one of our fellow instructors, I'm sure it's still in use as a loaner and more. Let's see if he chimes in.
Jerry

Rock River now sells a dedicated 22 upper.  I have been wanting to try it.

Quote from: Jerry Hall on February 21, 2020, 04:47:49 PM
I had the opportunity to use a CMMG dedicated upper .22 cal. several years ago, during the break-in period. In the beginning the upper was firing around 6 MOA, at about 300 rounds through the barrel the group size decreased to around 2 MOA. The upper belonged to OLAdcock one of our fellow instructors, I'm sure it's still in use as a loaner and more. Let's see if he chimes in.
Jerry

I would be very interested in theories about the bolded part above. What happens that makes it go from 6 MOA to 2 MOA? Thanks in advance.

I have a CMMG upper purchased from PSA that was under three bills.  With CCI Standard Velocity it holds 2 MOA or less.  It stays under 4 MOA with bulk junk.  I have not tried to find the "Favorite".  My CMMG conversion was maybe 6MOA, but the upper has made several riflemen.

Quote from: ArmyVet on February 21, 2020, 07:34:31 PM
I would be very interested in theories about the bolded part above. What happens that makes it go from 6 MOA to 2 MOA? Thanks in advance.

Me too. Maybe burrs in the barrel that got smoothed out? Or lead from the bullet filled in some gaps or something?

Anyhow the Tippman M4-22 is a very good choice. https://appleseedinfo.org/smf/index.php?topic=54831.0

Kinda pricey but worth it. Might still be able to get you one with the Appleseed logo engraved on the receiver. If interested PM me and I'll contact Tippman. Plus we do still get an instructor discount which puts it at $419.

Just to keep things clear:

The original post was not about a dedicated 22 upper that I'm all for but a conversion bolt kit that will only shoot 6 MOA on a good day.

I use the conversion bolt kits discussed here. I got 30 moa accuracy with 40 grain ammo. When I switched to 60 grain I went back to the 1 moa my rifle will shoot. Needless to say that the difference was incredible.
The only problem is that Aguila is the only manufacturer of 60 grain .22lr, and they make their propellant out of sand.
I like the ability to train a my AR cheaply ( and quietly) .

Quote from: Charles McKinley on February 21, 2020, 02:19:35 PM
5.56x45 bullet is .224 in diameter.

22 LR is .221 in diameter.  Expect 6 Minutes of Angle at best from a conversion kit.  The bullet bounces down the barrel like a musket ball.

The sizing of the bullet to .224 might help. See here the Accurizer https://www.gunblast.com/Paco.htm

Quote from: CarrollMS on March 16, 2020, 11:24:35 PM

Quote from: Charles McKinley on February 21, 2020, 02:19:35 PM
5.56x45 bullet is .224 in diameter.

22 LR is .221 in diameter.  Expect 6 Minutes of Angle at best from a conversion kit.  The bullet bounces down the barrel like a musket ball.

The sizing of the bullet to .224 might help. See here the Accurizer https://www.gunblast.com/Paco.htm

Hmmm...all of a sudden, I'm fascinated...

Quote from: Lomshek on February 21, 2020, 03:11:32 PM

Quote from: Charles McKinley on February 21, 2020, 02:19:35 PM
5.56x45 bullet is .224 in diameter.

22 LR is .221 in diameter.  Expect 6 Minutes of Angle at best from a conversion kit.  The bullet bounces down the barrel like a musket ball.

I doubt you mileage varies that much from others experience.

6 MOA is the best I could get with a Ceiner kit (which the CMMG is a copy of).  That was in a Bushmaster 1:9 A2.  I've not seen anyone do better but there are some reviews where guys have done better online.

In a Daniel Defense 1:7 it shot a stellar 30 MOA group!

I'm converting my conversion bolt into a dedicated .22 upper for real accuracy and practice.

The nominal caliber for the 22 long rifle projectile is generally given as .223" although the actual specification per SAAMI is 0.2255 with a tolerance of -.004".  But those who have measured the actual projectile diameters of commercial 22 LR ammunition have found diameters ranging from .221" all the way up to .225".  For example, James and Kathleen House in the second edition of "Customize the Ruger 10/22" state that they have measured Remington 22 LR Target ammunition bullets in the 0.224-0.225" diameter range.

Of course, there is some variation in groove diameter of 22 LR barrel bores as well, which is one reason some ammunition types shoot more accurately in certain barrels than others do. 

Certainly, AR barrels chambered in .223 Remington are going to have a bit larger groove diameter than 22 LR barrels so choosing a 22 LR ammunition that tends to have a generous projectile diameter might improve accuracy.  Such ammunition includes CCI Stingers, Mini-mag, and Blazer, Remington Target and Golden Bullets, and Aguila Super Extra.

I'm liking the idea of the paco tools for my squirrel hunting!

Quote from: eaglescouter on February 21, 2020, 10:35:07 AM

Quote from: cowtipper on February 21, 2020, 08:56:52 AM
Does anyone have any experience with the CMMG .22 LR conversion kits for AR's?

I have seen participants use them at more than a few Appleseed events, and they do function well. 

Most of the conversion kits I have become aware of on the line came to my attention due to good shooter technique and form, combined with excessive group size.

Your experience may be different.

"excessive group size" - that was my experience as well.

Tried the kit in 3 different uppers, they all worked with CCI SV but the results downrange were unsatisfactory. I believe it's an issue with barrel twist rates.

At 25 yds, CCI SV would easily hold inside an inch at 25 yds out of any of our 10/22's.
With the conversion kit and a 1:8 or 1:9 barrel best group was in 5" range.

Very disappointed. Returned to point of purchase (Brownells) for full refund.

Worth the upgrade to a dedicated upper. The barrel and bolt are the difference between a 5.56 build and dedicated 22lr.  CMMG are good, if you can find an TACCOM bolt and barrel grab it. Black dog machine makes good mags for the 22AR.

MAHA

I've got the CMMG conversion bolt for my AR15's.  It's awesome and a lot of fun, with CCI AR Tactical Ammo.  My AR has a 1-in-7 16" Barrel, an awesome trigger and a great Vortex scope.  I've zeroed the scope at 50Y/200Y with 5.56 77grain, results with the .22LR are below
25M & 1" Groups (8MOA dialed on scope)
50Y & 1.5" Groups (6MOA dialed on scope)
75Y & 2" groups (8 MOA dialed on scope)
100Y & 4" groups (13.5 MOA dialed on scope)
200Y on steel (26 MOA dialed on scope)
300Y on steel (46 MOA using the 20-moa line on the scope)

With a good AR rifle setup and using the fundamentals, the hits are repeatable all day.

Best part of the .22LR, my boys (5-YO twins) have a great time shooting with me!

I have two of the CMMG kits and like them a lot.  In fact, I liked the first one so much I got a .22 LR AR barrel and "converted" the it into a dedicated .22 AR.  I only use it with a red dot for Steel Challenge and have not really shot it for groups so can't attest to accuracy.  I then bought a second to have a conversion to use in other ARs.  Both very reliable with mid to better ammo and I have no complaints for what they are.  Honestly, I do not expect tack-driving out of a conversion, the dedicated rifle I expect more but did not build it for that.  I have bull-barreled 10-22s and stuff for attempting itty-bitty groups.

I've used the adapter from Brownell, works fine but full ammo is always best of course

I used the CMMG conversion for about a year and a half with my standard AR upper.  There were initially problems with failure to eject and jams.  Switched to the RTB (Righttobeararms.com) charging handle and backed it up with the buffer plug and most problems went away.  I did have problems with one of the CMMG mags so don't use that one any more.  Accuracy was OK and certainly good enough for speed steel. Later on, I ended up with a spare completed lower so decided to build a dedicated .22 upper.  Bought an RTB slick side upper, Tacom3 tension barrel and collar https://taccom3g.com/product-category/for-ar-15-22lr/, and an AT3 handguard https://www.at3tactical.com/collections/handguards-quad-rails . Watch for sales if you're not in a hurry.  I was also able to get some 10 round Black Dog mags.  Was having problems with light strikes and failure to feed that I tracked down to a broken firing pin. Bought the enhanced firing pin from RTB and also added the BCG weight to fix extractor issues and bolt bounce.

The upper was good enough for me to earn a rifleman patch at my first Appleseed shoot last weekend.  I don't believe I would have had any chance at it with just the CMMG conversion in a standard upper.

I've used the CMMG conversion kit in my AR mostly to save ammo $$ for general training.  I've bench rested it at 25 yds and found the accuracy acceptable for training purposes, but not for target precision purposes.  Based on the spread, I think it would be even less acceptable at 50+ yds.

I shot my first Appleseed in April 2021 with my AR using .223 55gr.  I did not qualify as Rifleman but didn't expect to, as I am a fairly new shooter.

Afterward I got the CMMG kit to save $$ on ammo, as said above.  I wasn't convinced it would be satisfactory for Rifleman qualifying at my next Appleseed, so I bought a T/CR 22 instead of trying to use the CMMG at the next event.  I did qualify as Rifleman with the T/CR 22 last weekend.

I still use the CMMG for general training but I think I'd prefer a complete .22LR upper if I wanted to shoot .22LR out of an AR in an Appleseed shoot -- at least if I wanted Rifleman or better.  I may build a complete upper in the future for that purpose, if time & money allow it.