I started to develop loads for my 7x57 which has a 21 inch barrel. I started loading with
H4831 and used the Speer and Sierra loading manuals for reference. I started off with 50 grains and worked my way up to 53 grains which was the max in the Sierra manual.
Here is what was strange. With 51 grains, the velocity was 2575, with 52 grains it was 2615, and when I went to 53 grains the velocity actually dropped back down to 2585 average over 5 shots. Even though my barrel is only 21 inches, these velcities seemed quite low. Do you think my powder has gone bad?
I then tried 42 grains of IMR 4064 and chronographed 2700 fps which was more like what I expected.
Any insight as to why the H4831 is not performing?

Just a stab hear but H-4831 is quite a bit slower than IMR 4064 and your 21 inch barrel may not be enough to take full advantage of the slower powder.

Forgot to add, it sounds like you are using a 130 grain bullet, if you have any heavy bullets try them with the slower 4831 and see if you get velocity closer to what you should have.

I load 50 gr. h414 162gr hornadys 19in barrel get an average of 2800+. fws

Listen to Toto, H414 is the only powder for the 7x57, I have been using it for years and I get unbelievable velocitys in my long throated 7x57...I use a bit more powder in grs. than Toto, because of my long throat and I get more velocity...160 gr. Nosler at 2919 FPS.

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Ray Atkinson

ray@atkinsonhunting.com
atkinsonhunting.com

Primetime. First off, H-4831 is a bit slow for the 7X57. usually, velocity increases in a linear fashion until a maximum load is reached. At that point, velocity increase will be much less, or even less than the load just prior to the load with the "strange" decrease. I believe you went past the max load for the bullet you were shooting. Nice thing about chronographs. They can tell you all sorts of thing, if you can read what they're saying.
Paul b.