Reloading for 7mm Mauser

[amadeus76]

Interesting question. I have a box of Chilean military 7x57 dated 1976. It is loaded with a 138-grain FMJ spitzer bullet. This is a clue but the real answer involves some math.

On my M1912 Chilean, the rear sighting surface moves vertically .26" when raised from 300 to 1000 (meters). Given the rifle's 25.6" sight radius, this corresponds to a difference of 34.91 minutes of angle - reasonably close to the calculated "come-up" from 300 to 1000 meters with a projectile having a BC of .425 at 870 m/s muzzle velocity (2854 fps). This velocity is entirely within the practical span of acceptable-pressure loads from the 29" barrel of the M1912.

By contrast, the old 170-grain RN bullet at a practical 750 m/s (2460 fps) would need a come-up of almost 70 MOA from 300 to 1000 meters. It therefore seems reasonable to assume that my M1912 is sighted for a faster spitzer much like my Chilean military sample.

You're my hero of the day!!

I thought it would be the 138gr pill as most people I've talked to say they've had great luck with 140gr bullets, but I couldn't find anything conclusive. Thanks!

[Parashooter]

You might check the sight movement on your 1912. It might be different from mine - since it's possible they were originally made for 170 RN projectile and some didn't get an upgrade for the spitzer. Just measure the difference in effective height from 300 to 1000. If it's close to .26", it's like mine.

[ireload2]

Your requirement for match bullets may need to be reconsidered. They are long and pointy with boat tails.
I own (2) 7X57 rifles a tang safety Ruger 77 (3X9 scope) and a near mint 1895 Chilean Mauser mfg in 1895 (sights are original on the 29 in barrel.

The accuracy of both of these rifles was indifferent using a variety of 140 grain to 160 grain boat tail spitzers. I have also shot some of the Hornady Match bullet with the same accuracy - about 1.5" to 2" groups at 100 yards.

I found some Federal Classic 7X57 factory ammo that was very cheap and bought it. This was the plain jane 175 grain RN soft point.
Shooting this ammo at the range in both rifles was a shock. Both rifles grouped about one inch for 5 shots. That is unusual for the Mauser because that is right at the limit of my eye sight with the factory iron sights.
I have also shot Norma factory ammo, Hornady Frontier and Remington ammo at the same time with the same results as my handloads about 1.5" to 2".

I have since loaded 175 grn RN Herters and Hornady bullets and got tiny groups with both of them.
The 175 grn RN bullets seem to be far superior in accuracy in my 2 rifles.
My only other 7mm rifle is a Ruger #1 in 7mm Mag. It gives the same accuracy with the lighter spitzers. I have never tried the 175 grn RN bullets in it.

[Bruce McAskill]

Also depends on the rate of twist in the barrels. Normal rate for the 7x57 was about 8.5 to 8.75. Some newer rate of twist is in the 9.25 or higher works for the lighter 140 gr. bullet and still will stabilize the 175 gr. class. Original loading velocity for the 175 gr. was 2200 fps and later updated to the blistering 2450 fps. But with the 175 gr. bullet it is a penetrator that takes a 200 gr. in the 30-06 to match it. But the 7x57 is such a joy to shoot.