I have a CMMG conversion for my CMMG M4 and I like it a lot. I used to run it thru an olympic arms AR and it wasnt reliable. However in my CMMG AR it goes bang everytime. It isnt as accurate as the 5.56 but its definately good for plinking and training. I dont really shoot it beyond 50 yards with the conversion. It doesnt have a preference on ammo. It will shoot copper jacketed hollow points, lead, etc. It does make mine pretty dirty especially with lead. I always make sure to clean it really good after shooting it. Just as my rule of thumb i fire 250 rounds of .22lr before cleaning it out. But for me it was a good investment. I can fire 550 rounds for $20 instead of several hundred $$.
I really like mine. It runs great with any kind of ammo I have put through it. Also as a perk, I will through on the spectre and use subsonic rounds. All you here is the bolt and a thud at the end of the range.
i may be in the minority here but defintally no for me. the rate of twist on a standard ar upper is all wrong for a 22 lr. basically meaning it will be inaccurate. ive been told i have to high standards but for me plinking is no fun and training is no good when the bullet doesnt go where i tell it to.
i went with a mp 15-22. its no match rifle but its accurate enough for plinking, training, and not raising my blood pressure