I have two Cooper rifles.
A M54 Varminter in 22-250 and a M52 Jackson Game in 280AI. The fit and finish of both is superb. Both shoot really well.
The 22-250 shoots 5 shot half MOA groups all day long. It is the most accurate rifle I own out to 300 yards. Once in a while it will just seem "tuned in" - way under half minute (maybe always capable of that and I'm not
). I had a pre-load development box of reloads that I decided to burn on my new 4" square AR500 plate. While I'd like to blame the verticle spread (1.2") on the fact that they weren't optimal reloads, I think it speaks for itself. 280yds.
The 280AI is also a shooter. It shot a 10 shot MOA group at 100yds while I was doing a pressure work-up. Load development was a cinch - not picky at all. It is a solid half MOA rifle with both 160NABs as well as 168 Berger VLDs. Good example of not-picky.
My experience with Cooper rifles has been awesome. I have several high-end, known builder customs that don't shoot any better. I would bet you will not have any buyers remorse if you go that route.