7.62x54r Ammo

[biscuitninja]

I am trying to figure out barrel pressures for my 91/30 Mosin Nagant.

The ammo I'm currently using is the Bulgarian heavy ball ammo. Any ideas?

Some information.

182 grain bullet

power/propellant - Unknown - 63.9 cc volume and 47.2 cc of propellant.

Ballistic Coefficient - .368

Sectional Density .269

Dia. .311

Barrel Slugged at .309/.311

Velocity average 2621 fps.

any ideas let me know.
-bix

[alpha_romeo_XV]

A look at www.hodgdon.com for 7.62x54R reloading data gives a few examples that are probably close. I don’t think barrel pressure is commonly nor easily measured by the average reloader.

Bullet Weight (Gr.) = 180
Powder = Hodgdon Varget
Grs. = 46.5C
Vel. (ft/s) = 2575
Pressure Grs. = 45,900 CUP

"CUP is an acronym for Cooper Units of Pressure, a rather old method of measuring maximum internal pressure in a firearm. It was measured using a small piston pressing against a piece of pure copper and observing the amount of distortion (flattening). PSI (Pounds per Square Inch) is a more modern technique, usually using a strain gauge taped to the outside of the chamber. There is no way to convert CUP to PSI so any pressure measurement data you see will be one or the other."

[Ironchef]

I think I read somewhere that the 91/30 pressure is like 75k PSI. It was in a forum where they were talking about leaks and how explosive it is in their and why it heats up so much and melts finish out of stocks.

[virulosity]

54r is definitely a higher pressure round. For your purposes though, why risk it? Just start low and build your way up.

[ar15barrels]

I am trying to figure out barrel pressures for my 91/30 Mosin Nagant.

While this does not answer your exact question, I can tell you that the CIP spec for 7.62x54 ammo is 3900bar, or 56,565 PSI.

[ar15barrels]

I think I read somewhere that the 91/30 pressure is like 75k PSI.

Don't believe everything you read on the internet.

[biscuitninja]

While this does not answer your exact question, I can tell you that the CIP spec for 7.62x54 ammo is 3900bar, or 56,565 PSI.

That's kinda the answers I was coming up with.
There is kinda a round about conversion, to CUP, but it involves the Material/mechanical properties (modulus of elasticity and a few other items) guessing at piston size, and deformation of copper (as well as hardness)
Anyways I came up with about 54ksi to just over 61ksi. Not a HUGE range but about 57ksi +/-3ksi (about a 5% error).

Not exactly bad for a semi educated SWAG.
anyways good luck
-bix