In my 303's, I've tried the following:
165 grain 308 Hornady InterLock's + IMR4895 - shot very well in my 303 that has the 2 groove rifling in the barrel, not so well in my other one with standard rifling, no critters shot with this bullet (at least not out of a 303 - it's worked well out of a 308).
123 grain Hornady InterLock + Red Dot (reduced load) - shot poorly in my 2 groove, shot well in my other one, no critters shot with this bullet (just a "plinking" load).
180 Grain Sierra GameKing's + Reloader 15, and later, BL-C(2) - shot very (very) well in both of my 303's (in the 2 groove, it would shoot 1/2 inch groups, actually, WOW!). I loaded them up to 2450FPS and that year I went and shot a mule deer with this bullet (3 times, from inside the 30 yard mark). The deer died (slowly), and on the post-mortem, none of the 3 bullets appeared to have expanded, I would NOT recommend them for hunting purposes, EVER!
180 grain Winchester PowerPoint factory ammo - shot well in both of my rifles, and performs excellent on critters.
150 grain Federal factory ammo - didn't shoot worth beans in either rifle.
My next round of loading for my 303's (in progress, currently, actually) is three different combinations:
150 Grain .312 Hornady InterLock's + Varget
150 Grain .312 Hornady InterLock's + Win 760
180 Grain .308 Winchester PowerPoint's + Win 760.
We'll see if either of those shoots straight in both guns. In all cases, I'm looking for a fairly low pressure load that shoots straight - not chasing velocity at all, as I don't like buying new brass, and the 303's will eat brass bigtime at even "normal" pressures.
And side note - I think the 760 is probably going to turn out to be a bit slow for 150 grain bullets in the 303 case, but I've got a bunch of it on-hand, and I need to find something use it for other than 220 grain bullets in my 308's, so I'm giving er a try - if it'll just work half way well, I'll be happy.
