Long Barrel on 300 Ultra Mag

Darryl Cassel

Well-Known Member
May 7, 2001
If you don't care about case life, you may get close to that velocity but, very doubtful.
Comparing my 30/378 with 220 and 240gr bullets and a 37" barrel, I can, however the case capacity is a bit more then the UM plus it's on a custom large action.

What twist rate, barrel length, bullet weight would you use for the .300 Ultra Mag in 1kBR? I had been wondering about the possibility of using that round and read that someone shot best group AND score with it at Williamsport over the weekend.
He didn't get best Group. The World Record group is 4.534" ten shots and is held by Joe Lesley. John Buhay won the SCORE World Record this past weekend with a perfect 100 with 5xs and a 5.377" Group witch was a smaller group then John Hoover had with his 100 score and 5Xs. The ties are broke with the group fired in this case.

The rifle was his own design and chambering. He has a 30" Hart barrel 10 twist, used RL 25 powder and 200 Gr Sierra Matchkings.
The scope was a Leupold LR 8 1/2 to 25X and the action was Remington.

It's the first 300 UM that I have seen shoot accuratly with the several that have been tried at Williamsport. Most have given up on it. This one was an exception I would say.
The brass is the problem. Only Remington at present from what I'm told.
That's the story and I was there.
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