7x57 Load Data

[denton]

The day I've been waiting for since March finally rolled around: Clear skies, comfortable temperatures, the range open, and some time off work to work up loads for my 7x57. So here's the data....

My rifle is fairly long-throated. With 162 Hornady BTSP's I use a COL of 3.190", and am about .050" off the lands. That will probably produce lower pressure and velocity than many other rifles. The brass was new Remington brass, which seems to hold about .5 grain more powder than another type I've tried. Primers were CCI 200. The following data is for reference only, since your rifle WILL behave somewhat differently, and your bottle of powder is different from mine. Data shown are the best-fits results from regression of the raw data. That averages down the noise a bit, and gives a more reliable result. Pressure data were taken with the PressureTrace strain gage. Muzzle velocity was taken with a Shooting Chrony. Ambient temperature was 62-65F. I did not take the time to hook a thermocouple up to the barrel as I sometimes do, but I did let the barrel cool between shots so that it felt about 75F-ish.

162 Hornady BTSP, H4350, COL 3.190"
Grains....PSI.........FPS
43.........34,402.....2380
44.........37,967.....2445
45.........41,533.....2510
46.........45,098.....2575
47.........48,663.....2640
48.........52,228.....2705
Comment: 3565 PSI per grain, 65 FPS per grain.

162 Hornady BTSP, RL19, COL 3.190"
Grains....PSI............FPS
47..........43,524.......2481
48..........46,659.......2551
49..........49,794.......2622
50..........52,928.......2692
51..........56,063.......2762
Comments: 3135 PSI per grain, 70 FPS per grain

150 Sierra BTSP, H4350, COL 3.090"
Grains.....PSI...........FPS
45..........34,677.......2507
46..........38,598.......2579
47..........42,250.......2652
48..........46,441.......2725
Comments: 3921 PSI per grain, 72.8 FPS per grain. 48 grains is getting near a full case. Might benefit from a slightly faster burning powder, or a little more H4350 if it will fit.

Sample of 1: 52 grains very old H4831, which is a case full to the brim, and 150 Sierra, 44,000 PSI, 2635 FPS.

53 grains H4831SC, 150 Sierra, 2730 fps, no pressure data.

This is a #1 contour barrel rifle, so it is fairly light. So far, it seems like an ideal combination of performance and weight.