Home Forums Reloading Big Game Rifles Good 7x57 Mauser loads

Well the custom 7x57 has been retired for the duration while I consider what to do with it. I'm thinking there's a problem with the chamber but not sure what.

I have decided that the 160 gr. Speer Grand Slam/H4350 combo is probably a losing proposition in both rifles. (M70 and the Mauser)

I decided to try Rl17 and the 150 gr. Nosler Partition in the M70 FWT and may have come onto Nirvana. I loaded up six different charges of Rl17 starting with 47.0 grains and going up in half grain interval up to 49.5 grains. Results are as follows.

1. 47.0 gr. 2710 FPS avg 26 FPS ES one inch perfect equilateral triangle.

2. 47.5 gr. 2751 FPS avg 19 FPS ES group triangular .375"x1.0"

3. 48.0 gr. 2743 FPS avg 30 FPS ES group triangular .25"x 1.375" *

4. 48.5 gr. 2847 FPS avg 39 FPS ES Group .75x .002" (002." estimated as it's just one slightly enlarged hole.)*

5. 49.0 gr. 2883 FPS One shot fired.

6. 49.5 gr. 2910 FPS One shot fired.

*No pressure signs whatsoever on any of the loads. Primers all have nice rounded edges on brass that have been reloaded several times already with pocket while not very loose are still not as tight as new brass. Even case head and pressure ring measurements show little signs of pressure.
However, I'm a firm believer in that powders are designed to burn within high and low parameters and that pressure/velocity increase is relatively linear within those parameters. Any change either a large increase, no change in velocity or even a drop in speed is an indicator that one has reached the top parameter for the powder in question. Note the change from load #2 to load #3. Even load #4 is slower than Load #2 although not by much and then load #5 had a large jump from only one shot. The same from load #6. Both #5 and #6 are at load levels found in the .280 Remington.

Final decision is I'll go with load #1. It sufficiently fast enough and certainly accurate enough to be minute of cow elk.
If anyone wants to try Rl17 in the 7x57, I'm thinking I started a bit too high. Probably should have started at around 45.0 gr. and worked up from there.

For spits and grins I also took the .280 Remington out for spin using 57.8 gr. WMR (Winchester Magnum Rifle powder and the 160 gr. Speer old style two core Grand Slams that were so troublesome in the 7x57's. Muzzle velocity was 2907 FPS with an ES of 79 FPS. I fired two three shot strings for .75" both times. Maybe I ought to take that one elk hunting.

Paul B.