Back when I got my Browning Eclipse in 300 WinMag, in 2001, I had an old Speer #8 manual that I had been using for years, and it had always worked fine. My go to powder for the 30-06 was IMR4350, so I found a load for the 300 Mag with that powder. My manual had a suggested starting load of 71 grains with a 180 grain bullet. I stopped at 73 grains of IMR4350 with a chronoed result of 3140 ft/sec. No pressure signs and good brass life. I was surprised when I got a newer manual where it showed a max charge of 69 grains of IMR4350.
That73 grain load shot 3/4" groups pretty consistently.
Last edited by the_shootist; 04/22/14.
