Too hot?

[Major Tom]

I have some Hornady 45-70 factory rounds. They have the 300 gr. red tipped bullet. I am wondering if these are too hot for an original M84 trapdoor.

Information

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[jmoore]

Very, yes, too hot! Unless the velocity listed on the box is about 1200-1300fps. Even then, not recommended. stick to lead projectiles.

[Patrick Chadwick]

As a rule, BPCR rifles were dimensioned with groove depths suitable for lead bullets. The 45-70 has an astonishingly short throat that is more of a bevel on the end of the rifling than a gradual transition. OK for lead, but it places a much higher stress (=pressure) on the rifle if jacketed bullets are used. Take a look at the Lyman Reloadng Handbook, Hodgdon Data Manual, Sierra Rifle Reloaing Manual etc. They all warn that a trapdoor must be kept to much lower pressures than more modern rifles.

Patrick