I had no issues. The bolt is balanced for 40gr and above ammo, so it didn't cycle reliably with the lighter stuff. This is made clear in the info that comes with the rifle so no surprise there. An occasional spray of light oil on the bolt makes it run smoothly, and keeping it clean; but no need to be too fussy. 45gr Hornady critical defence ammo expands really well, and grouped well too; so that was my preferred ammo. I fitted a better pistol grip with a rubber finish, all AR15 parts fit so swapping bits about is simple. 22wmr is quite a step up from 22lr in power and bark, so I usually ran it with a mod on. Great fun at the range on steel gongs!
I moved the rifle on to fund another purchase, but positive comments all the way on it. I believe there is a waiting list for a new one, they make them in batches once enough are ordered I was told.
Thoroughly enjoyed mine. Hope this helps?