CMMG .22lr conversion - a brief review

**lindertw** · 11-05-08, 20:36

A few weeks back I placed an order w/Brownells for a CMMG .22lr conversion kit w/27-round magazine. I got an email on 03NOV that it shipped, and it arrived today

The planets aligned and I managed to squeeze out of the house this afternoon to try it out. I was in such a hurry I didn't bother to give it a quick once over before heading to the range - specifically I didn't bother to lube it beyond the sparse oil that was on it from shipping (more on that later)... gotm4 was at the range, and I got to meet 9x19, and Pk14 - great to meet you two! LittleLebowski was also there, but he was with someone on the line so I chose not to interrupt/introduce myself...

This is the first conversion unit I've ever used/laid hands on - so I don't know if it's better than any other. It seems to be pretty solid, and functions smoothly. It weighs 10.1oz, ~1.9oz lighter than the Colt BCG that I pulled out of my 6920.

I ran 250 rounds of American Eagle 5022 40gr lead ammo down the pipe with minimal problems. What bobbles I did experience I can almost certainly attribute to the complete lack of lubricant! I only loaded the mags w/20 rounds at a time (it was tough to get 23-25 rounds loaded, and I don't think I'd ever get 27 rounds in there). Once I've got 1-2k down the pipe and it's all settled in I'll try to load the mags to capacity.

After the 250 rounds of .22lr, I switched the 6920 BCG back and fired 20 rounds of XM193 in an effort to clean out some of the funk.

POI was pretty much spot on factoring in the holdover while I was shooting at 10 yards - obligatory pic attached:

Shooting .22lr from your AR is a hoot

I can now shoot the snot out of this and not feel guilty about using up my stash or how much it costs. Additionally, my 7yo daughter is going to have a blast with this (heck, I've still got a grin on my face).

Next up is a few more Black Dog magazines and a ton more ammo.

**Pk14** · 11-06-08, 15:46

Great to finally meet you in person yesterday - sorry I couldn't stay to see how the CMMG conversion kit worked!

Have you had a chance to see how much residue was left after the 20 rd 5.56 cleaning rounds went through the barrel?

I saw a TacSol dedicated upper last week at NRA - thinking about how much extra $$ it would take to configure that upper into a reasonable clone of my N4 verus the CMMG option - seems like it would be better to go the CMMG route and spend the difference on an SBR upper set-up (which could also use the kit).

That RIS II rail and SF x300 is a great set-up on that 6920!

Cheers,
Pk

**lindertw** · 11-06-08, 16:01

Pk,

the barrel cleaned out just fine after the 20 rounds of 5.56; however the chamber and the conversion kit were filthy when I got home. I meant to take pics before I cleaned it but my OCD kicked in...

I'm going to experiment with several brands of ammo, and I hope to find a reasonably priced (read cheap) copper plated bullet that the conversion likes. I can't say for certain, but I think the copper plating will give leave less funk in the barrel for me to clean out. No matter what I plan to run 20-40 rounds of 5.56 down the pipe at the end of each .22lr session just to clean junk out.

I was on the fence WRT conversion kit or dedicated upper, and the cost factor pushed me towards the conversion (I look forward to putting the saved $ towards ammo). Brownells has an excellent return policy, so I figured if the CMMG kit didn't work out I could pursue other options.

gotm4 will be installing at least one (maybe two) of those RIS II rails tomorrow. You could always add yours to his assembly line; as of yesterday afternoon VA arms had one brown/one black RIS II rail left on the shelf - you know you want it

**austinN4** · 11-06-08, 16:20

Originally Posted by lindertw

I'm going to experiment with several brands of ammo, and I hope to find a reasonably priced (read cheap) copper plated bullet that the conversion likes. I can't say for certain, but I think the copper plating will give leave less funk in the barrel for me to clean out.

My Buck Mark and Marlin 60 both like Remington Golden, so I am hoping my CMMG, when it arrives in a few days will like it also. I'll post results.

Originally Posted by lindertw

I was on the fence WRT conversion kit or dedicated upper, and the cost factor pushed me towards the conversion (I look forward to putting the saved $ towards ammo).

I was on the fence also, but went with CMMG due to recent positive reviews after it started shipping. And the money I saved went into 1,000 PRVI 5.56. I bought mine directly from CMMG, but I figure if it doesn't work out I can always sell it and go with a TacSol upper later.

**FromMyColdDeadHand** · 11-07-08, 17:52

How does the Bolt open feature work?

**lindertw** · 11-07-08, 18:38

The magazine holds the bolt back after the last round, but when you drop the magazine the bolt rides forward - insert a fresh mag and pull the charging handle to go hot...

**Pk14** · 11-08-08, 05:43

Originally Posted by lindertw

Pk,

gotm4 will be installing at least one (maybe two) of those RIS II rails tomorrow. You could always add yours to his assembly line; as of yesterday afternoon VA arms had one brown/one black RIS II rail left on the shelf - you know you want it

Don't be afraid of the light, Caroline! Walk into the light!

The conversion kit will certainly offset funds for a dedicated .22 upper, but I've got to queue up the SBR build first. That, PMAGs, ammo, new scope (Thanks for the quick-look Robb!) a 6.5 G upper and a rebuild / upgrade of my CZ-75 are going to keep my discretionary account tied up for a little while. Damn BRD!

Pk

**lindertw** · 11-09-08, 13:26

mini update:

I was able to put another ~300 rounds down range last night, and I tried two additional brands of ammunition.

Winchester 36gr copper plated (333-round value pack)

-experienced a moderately high rate of failure to go bang.

Aguila Super Extra 40gr copper plated

- could not get even one round to fire (loaded/tried ~40 rounds).

Weird, the Aguila works like a champ (and is pretty accurate) in my Ruger MKIII 22/45.

It looks like I'll continue the experiment with various types of Federal/American Eagle ammo, as that consistently works so far.