While I agree that a dedicated firearm is better, I bought my CMMG conversion bolt before .22 uppers were even available and I must say that it has never let me down.I have always preferred dedicated firearms as opposed to conversion kits. Conversion kits always seemed to stay home when I went to the range.
I have a conversion kit for my G3K. Once I got the dedicated upper for the M-16 that H&K kit got parked. Matter of fact the only .22 that is still of any interest is my integrally suppressed Ruger 77/22, aka my lawn lion gun!I've got .22 conversions for my Sig P228, P229, and also for my HK91, HK93, and MP5. I've got an AR upper specifically set up to swap over to one of my ARs, so that when in-use, it's the proper 1:16 twist rate for the .22LR. I've got the .22 conversion for my HK Model 4 pistol, and I seriously wish that someone would make/sell in the US a .22LR conversion for the HK USP/VP9/etc.