Just received my shipment of 8x52R Siamese from Buffalo Arms thanks to Bill/Oregon's suggestion. Also received 700 rounds of corrosive Turkish 8x57 from J&G which will be used for powder and bullets for the Siamese reloading project.

My question is how to go about finding a safe starting load using the salvaged powder?

The bullets are 154 grain German "S" type .323 in diameter. The Siamese bore slugged out to .323 also.

The powder appears to be German flake type. Average load in the 8x57 samples is 48.5 grains.

Case capacity in grains of water is 57.5 for the 8x52R and 61.6 for the 8x57. Difference is 6.66%.

I'm figuring if I reduce the load by that amount and further reduce it by another 10% for safety I should have a safe starting load to fireform with. It works out to about a 40 grain load. When poured into the 8x52R case it comes up to the junction of the case body and the shoulder.

What do you guys with experience in this area think?

Bobster,The theory you are using is sound when applied to strait walled cases but I have never used it with bottle-neck cartridges. If the shoulder angles are close and the diameter of the two cartridges is the same it should work.

Charge of the larger case times the ratio of the volume of the smaller case and larger case times .9

48.5 x (57.5 / 61.6) = 45.27
45.27 x .9 = 40.7

That should be a safe starting load. If your new case is larger diameter than the 8x57 then all bets are off due to the powder burn rate and the area difference. This is very close to internal ballistics engineering and will require your utmost attention to detail.

Good luck,
PaulS

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stay safe and live long!

I'm not sure if this would work but compare reloading data for the two with similar cartridges to double check. might give you an idea of ratios.

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A bad day at the range is better than a good day at work.

Most military powders are manufactured to operate in a very narrow pressure range and by nature are pressure sensitive. Load development can be very tricky with these powders as you can get erratic results below the optimum operating pressure and very quickly get pressue spikes above that very narrow pressure range. So be careful as the relationship between pressure, charge weight, and case capacity is probably not linear.