Tony

I bought some 3 inch magnum subsonic cartridges to use in my Baikai .410 hushpower.

I believe the marks on the barrel indicate that it is chambered to accept 76mm/3 inch cartridges however the proof pressure is marked as being 90Mpa and not 120Mpa, which if I am right in thinking, is the magnum proof pressure.

The bloke at the shop reckoned they were suitable however Im a bit weary about using them especially as the cartridge box says they are only suitable for guns proofed to 1200Kg/cm2 (magnum proof).

I believe 90Mpa = about 900Kg/cm2 and therefore 120Mpa = 1200Kg/cm2

Any advice, please.

Graham M

65 MPA = 9070 lb psi
68 MPA = 9489 lb psi
72 MPA =10047 lb psi
90 MPA = 12559 lb psi

If in doubt use 2¾” shells as a .410 does generate very high pressures.
G.M.

__________________
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Tony

Much obliged for your help Graham.

Think I'll stick to the standard loads just to be on the safe side, after all the explosion does take place only a few inches in front of one's face!!

Cheers.

Tony

clayman21

What is not always realised is that Magnum loads have two different aspects to their definitions, both length and max pressure define magnum. This comes about because of the length required for historic black powder loads ( longer case for more powder = higher pressures), and the fact that these same pressures can now be achieved with modern powders without the physical length being needed in the cartridge to contain the powder mass.

It is technically possible to prepare a 2" long magnum load, and I believe such loads have been available in the past. Although the case opens to a finished length of only 2", the powders inside it generate the higher pressures to which the "magnum" length chamber is tested, and could potentially blow the chamber of a shorter and lower pressure tested chamber.

It is therefore essential to use cartridges that are not more than the pressure rating of the chamber, but also ones that are not longer than the chamber length ( when open or fired, not the pre-detonation length).

Bit of a nightmare? Simple rules are; 1. know what your chamber length and proof pressures are; 2, read the cartridge manufacturers spec before buying or using cartridges.

This is actually fairly academic, as all modern shotguns are now tested to minimum proof of magnum pressures, so it really only of concern with an older gun, usually older English S/S which may have 2 1/2" or even 2" chambers, and lower associated pressure ratings.