I have two dedicated 22 AR upper's --- for my Rock River lower's. The match grade hammers will break after every 3,000 rounds using the dedicated ceiner and probably the Tactical Solutions bolts --- so you probably need to use mill-spec hammers and extra power hammer springs for proper detonation.
I've had major problems, especially with the Tactical Solutions upper. That is.... premature detonation of a 22 L.R. round, during a empty shell casing stovepipe, causing the rear sides of the shell casing too burst and a bullet squib load stuck in the barrel.
Tactical Solutions, sent me a tougher extractor ---- but the problem still exists.
The other dedicated upper --- a Model "1" from Texas --- has given me bulged rear 22 lr cases, and squib loads.
Conversion units are dangerous, if you allow 22 lr soot to accumulate so bad, that when you shoot a 223 cleaner round thru it --- will possibly crack the the bolt and break the charging handle in half; after detonation.