Haven’t caught up on the rest of the thread properly but.....If you're pushing out to 250-350 yards then a magnum won't do any harm at all. It'll offer a little more margin for error with wind and range and when shooting live quarry that's no bad thing. Not so sure about the Howa comment. For similar money you'll probably find a nice old rifle with a clean bore which will be much better quality. I've seen old Sako L series guns go for less than that and they're as good as they come.
you do realise that the howa is based (copied) on an old Sako action don’t you? I’ve owned 2, know loads of people that shoot them, incredibly accurate for the money. Lots of after market options.....