The 15/22 is a cracking RIMFIRE for the money and you can't go wrong. Myself I opted for a CMMG and only a few quid more than there top range.
I was looking for a working AR15 in .22 calibre, and would love to have the money to swap out the upper, to a .223
Have to agree, I use CCI ammo. No issues.
http://imageshack.com/a/img673/9679/zbeTob.jpg