Re: 300WSM in a 20\" barrel ??
I am shooting a 22" 300 RSAUM. Yes the muzzle blast is significant. Shooting 180 gr Nosler Partition factory ammo, I was getting 2997 fps. The same load in a 26" barrel netted 3200 fps. Back to the short barrel, I went with 150s because inside of 350 yards, my max visible range, they give me the best trajectories. I only give up an inch and a little in wind inside of 350 as well. I would suspect you can get 2950 with some max loads. They may not shoot the best, but that will probably be where you top out. I have visited with a guy shooting a Ti actioned 300 WSM shooting 180 gr NBTs, but his accuracy load was 2880 fps. He was shooting just under the listed max in the Nosler manual, and it was a max load in his rifle. His rifle had a 20 or 22" barrel on it too. Hope this helps.