Taking Advantage of AR Modularity

[Bart Solo]

Last winter I build an AR from parts.  Building the rifle was fun, and it is a tack driver.  Like a lot of AR's, however, these days it sits quietly in my safe.  I have other guns and the idea of spending that much money on ammunition holds me back.  My lower has an upgraded Guissele trigger that I really like.   
 
 Lately I have rediscovered 22 lr.  When I was a boy my 22 was my go to fun gun.  I still have my Remington Nylon 66 from back in the day.  These days I shoot my 22 buckmark several times a week.  The advantages of the 22 are (1) cheap ammunition and (2) good accuracy at tin can ranges.  Did I mention the ammunition is cheap. 
 
I have been reading about dedicated 22 uppers.  From what I read they have serious accuracy advantages over the dropin conversions, mostly because the dedicated uppers use 1-16 twist barrels. 
 
I wonder do any of you use a dedicated 22lr upper with your regular AR lower?  Do you find they create any problems?  What brand would you consider? 

[Bugflipper]

Will let the others answer the dedicated upper because I just use a conversion in a regular upper. With the match triggers a lot of them use a reduced power hammer and trigger spring. Sometimes the hammer spring isn't heavy enough for rimfire. I had a yellow jp spring that wouldn't fire. Had to go with a red one for the hammer spring and kept a yellow one for the trigger.

[Bart Solo]

I have read that some of the match hammer springs don't have enough power to fire a rimfire. That is something to watch for. Are there any other drawbacks to a dedicated upper, and which is best? I understand DPMS and CMMG are the two big names in the business and CMMG has a good conversion system.  I still like a 1-16 twist for a 22 lr.

[Lloyd Smale]

when i went shopping for a 22lr ar i priced uppers and read about the good and the bad. What i ended up doing is just buying a smith ar22. Its maybe not a true ar but its close enough and it goes bang EVERY time and is accurate. It also didnt cost anymore then an upper so theres allways a complete 22lr ar sitting in the safe.