When I bought the 6.8 SPC upper there were fewer choices than there are now. Ammo's not cheap, and I'm not shooting it enough to bother right now. I do reload 9MM and 40 S&W. And pick up any other brass that's nearby as well. I do have several hundred .223 and 5.56 empties that have been run through the tumbler.

I bought the 6.8 upper becaues it was available at a 'reasonable' price, and I wanted something heavier than 5.56.

I like my .22LR conversion as it works well and installs easily. Of course the 5.56 chamber needs to be nice and clean for it to fit as it should. I've had no problems, so must be doing a good cleaning job.