I am just wondering what sized bullet would best suit my barrel, its a 30cal with a 1 in 10"twist, 24" 300wsm I will be using Nosler Bts or Accubonds because that is whats available over here, have tried the 165gr but wondering if the 180grs because of there length being possibly better suited to the twist rate

Paul,

This is a 'pesronal choice' thing, and my preference is for the heavier bullet. Having said that, I seldom shoot anything at ranges longer than 200 metres.

It's not really comparing apples with apples, but my .308 Win, with a twist of 1:10", shoots 180gr solid-shank softs (a la Trophy Bonded Bear Claw) very well. At 2547fps, that's my standard hunting load.

I would suggest you give the 'heavies' a try - they might just surprise you!

The .300wsm really maxs out w/ a 180gr bullet in a short action. The 1-10 will stabalizeboth weights fine. It really comes down to what your bbl. likes, but I would start w/ 180gr bullets & work there.