Does anybody know of any heavy .22 ammo?  Im wanting to drop an m261 kit into my midlength and I thought maybe heavier ammo would fire better from a 5.56 barrel.  

www.firearmstactical.com/tacticalbriefs/volume3/number2/article3.htm

More than likely regular mini mags will work fine for you, there is also cci velocitors that are prety nifty.  The SSS is fun, quiet, and hits hard, but has a trajectory like a thrown rock and stinks  like mad when it is fired.

Quoted: www.firearmstactical.com/tacticalbriefs/volume3/number2/article3.htm More than likely regular mini mags will work fine for you, there is also cci velocitors that are prety nifty.  The SSS is fun, quiet, and hits hard, but has a trajectory like a thrown rock and stinks  like mad when it is fired.

Boy does it ever stink. It distracted me so bad I couldn't concentrate on aiming. People say Wolf ammo stinks but it doesn't compare to the SSS ammo.

I had problems with accuracy out of my Ruger 10/22 that has a Butler Creek heavy barrel. It is a super accurate rifle but it just doesn't like the SSS ammo. Some of the bullets keyholed at fifty yards.

However since you are thinking of shooting it out of your AR it may be more accurate with a faster twist rate.