What ammo were you using ? and did it have a standard trigger, my Howa 1500 stainless varmint has, and the pull is dreadful. Whilst mine is accurate at 100 yards with FMJ, I doubt that I could achieve a 2.5 inch spread at 300 yards, even from a rest.
As an aside, I'm not sure what stainless means to Howa, because in my case I've got rust on the receiver and barrel from getting drenched at Bisley a few weeks ago. It went rusty before I could get home and clean it.

Vic T