I just recived a manual from IMR,and was
looking at a load for 300 win useing 150 gn
bullet and IMR 4350 76.0 gn.Now i know to start you are to reduce loads 10% ,that put me starting at 70.6gn of powder.Before i got
started i looked up the load in two manuals
that i have.Horandy's starting load for a 300win 150gn bullet and imr 4350 is 63.3
and max 70.3 with3100fps .Speer manual
starting load 69.0 and a max 73.03173 fps.
while IMR max3335 fps. barrel's used were all
24''.allthough imr was pushing the max on cup
pressure 53900and max is54000.any thoughts on this

My recommendation...for the 150 in .300 Winchester...

IMR-4350 From 60.3 grains to 80.0 grains with Winchester WLR Primer

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http://stevespages.com/page8.htm

At http://www.imrpowder.com the max load for the .300 Winchester Magnum is 76.0 gr of imr 4350 and the 9 1/2M primer for 3335 fps.

That's if a .300 Win is a .300 Winchester magnum to you.

That's a good powder for the .300 Win mag. I like magnum primers for that load.