Re: Cooper rifles
I think you're wise to be wary of guarantees.
With any gun the wrong ammo will take it pretty far from potential, and there is no load data, much less best load 'desired' with a Cooper. This, as from most any gun maker.
That said, I have a Cooper M21 that very easily shoots 1/2moa with my ammo, and with some factory ammo(not just any).
I don't believe I've seen on a forum yet where someone ran into a problem with Cooper performance. And the only way I can resolve THAT, is to notion that Cooper buyers must be smart enough to realize they are not custom benchrest guns, but damn good hunting guns.
Yeah, I like to think that Cooper buyers are smart!