I bought a CMMG .22 Conversion Kit and just got done cleaning-up from my first day at the range with it. As I mentioned earlier in this thread, I've got a new (less than 200 rounds of .223) Colt, M4 Carbine 6920 LE
CONFIGURATION: My decision to buy the CMMG kit was an omage to my cyber-gun Guru, Nutnfancy. He has a wonderful review of the kit on YouTube (link is in my earlier post from this thread). I got my CMMG conversion kit from Brownells for $148 and I bought 3 BlackDog 26 round magazines (after research, the same style for the Ceiner conversion kit fits the CMMG) from cheapasdirt.com for @ $16.99 each. Finally, I bought CCI 40gr high velocity copper lined .22LR ammunition from Wal-Mart ($6.99/100rds).
I lubed the conversion kit up pretty well with CLP and played the mechanical bolt release before installation. Upon installation, my first reaction was that it fit into the bolt receiver like a charm. A few things I noticed during function checks with an UNLOADED magazine... (1) the bolt does not lock in the open position; (2) the bolt catch does not work... it does lock 2/3 of the way back when the empty magazine is inserted (you must move the bolt manually with the charging handle; (3) releasing the magazine is a little different... you need to pull the charging handle to back the bolt off the upper magazine tray, then punch the magazine release.
Now on to the range I went. As I loaded the magazines, I noted some stiffness after about 15 rounds were loaded. I decided to not push the 26 round max and loaded 20rds/magazine. I set my targets at near and mid-distance to check accuracy. I placed some multi-bullseye rifle/pistol targets at 25m and put a several 200m large bulls that were scaled to 100m at the appropriate distance. I didn't touch my stock iron sights that had been zeroed effectively with .223 one week ago.
With the range hot, I got to work. The first thing I noticed was the significantly different sound and recoil. I should have been better prepared for this, but honestly my first reaction was that I had a partial ignition of the propellent. After a few seconds of disorientation with this minor brain cramp, I realized that I'd had a smooth discharge, clean shell ejection and the next round had seated perfectly.
After the first 60 rounds were launched flawlessly, I walked down range to examine/replace my targets. My shot groups were slightly high on the 25m near targets, but the tightness of the shot groups was better than I'd achieved with the .223; so far so good. When I examined the 100m bulls, the rounds were dead-on. Nice shot group... a slight spread that was operator induced. Both of these results were improved on as I became more practiced. After 200 rounds, I called it a day and reserved the rest of the day to my Smith & Wesson and Kimber Pistols...
My first experience with the CMMG was remarkably positive. I have confidence that I will be able to push more cost-effective rounds down range without sacrificing too much of the realism that I enjoy with ownership of an M4. Sure, I'd rather be pushing .223 62gr down range, but for an 80% cost savings per round, the .22 conversion kit is well worth the purchase.