Duplex question

[jonk]

My trapdoor likes a duplex load of 5 gr of 4759 and about 55 gr of FFG, settled and the bullet seated to the powder. Anyone try duplex loads with Pyrodex? If truly an FFG sub, I don't see any issues- especially in my 71 Mauser, which is stronger than a trapdoor- which will be my test platform before moving over to the trapdoor.

[Don McDowell]

Pyrodex operates at alot more pressure than black. I'ld imagine that doing something as ignorant as duplexing might be the ruination of a fine old rifle, and possibly injury to the shooter. Don't much give a whizz about that, but sure would hate to see a fine old rifle that's survived this long to be undone by something that's absolutely not necessary.

[jonk]

If it burns w/ a lot more pressure than black, how do they say it is a substitute volumetrically?

Still, it is precisely b/c I don't want to ruin anything that I ask.

[Don McDowell]

A 70 gr volume poured charge of RS pyrodex actually weighs 56 grs.
Find a Lyman 47 manual and look at the 45-70 data in the Ruger #1 section, they have black and pyrodex loads with pressures included there. And as most pressure tested data shows, pyrodex runs half again as much pressure as a load of black.

[Boz330]

Or just call Hodgdon and ask, if it is unsafe I'm sure they will get back to you toot sweet. I tend to lean towards don't do it.

Bob

[bushka]

I did something like that in a uberti henry 44-40,something like 3 grains of unique and the rest pyrodex.I could actually feel the action/bolt "springing" on firing.
Some boom and flame tho,but like the fifth shot I split the case and had a helluva time getting the shell body out of the chamber.