I'm thinking of ordering some 250 grain cast gas-checked bullets from the Montana Bullet Works to shoot in my .375 H&H Mag rifle. Can anybody suggest powder types and amounts to shoot these bullets? Also, what is a good velocity range for this type of bullet? I have no experience whatsoever with cast bullets. Thanks.

I shoot the Lyman 377449 out of my M70 with 24" barrel. I usually cast these of WW/linotype at 60/40% and the weigh 270 gr fully dressed with Hornady GC and Javelina lube. I WQ them out of the mould to harden them. I size at .377".

I use 36 gr of 5744 (no filler) for a comfortable and very accurate 1860 fps. For a serious practice/hunting load I use them over 50 gr of 4895 with a 1 gr dacron filler. Velocity is 2200 fps and accuracy is still 2 moa.

Larry Gibson

Larry. I find your 4895 load very interesting.
I arbitrarily went with 49.0 gr. of 4895 with the RCBS 37-250-FN which is a close copy of your Lyman bullet. I'd estimated the velocity ato roughly 1850 to 1900 FPS but looking at what you got, I may have to upgrade my guessitmate up a tad. The load is accurate though at 1.25" at 100 yards which is about the best I can do with only an old all steel Weaver 2.5X scope on the gun. I like the great eye relief.
Paul B.

Paul B

Interesting in that my M70 also wears a Weaver 2.5X

A couple things to keep in mind; the dacron filler increases the burning efficiency of the powder. In a smaller case like the .308W it takes 1-2 more gr of powder to equal the same velocity when a dacron filler is not used. I'm not sure of the difference in the .375 H&H as I just arbitrarely used the dacron filler. That load has been chronographed numerous times over 2 different Oehler chronographs (M35P & M43). If you are not using a dacron filler then your velocities may indeed be down in the 1900 fps range. The 2200 fps velocity is in temps above 75 degrees (my usual temp range for "African" practice). It drops down to 2150 fps or so in the 40-65 degree range.

Larry Gibson

I've been using a case full (to the base of the bullet) of AA#3100 in my 375 Taylor and 300gr. cast bullets at 2100 fps. Great accuracy, and no pressure signs at all. The H&H should be about the same.