An interesting thought

[stubert]

If I'm loading a 300 grain cast bullet, from wheel weights, air cooled (soft). Or if I loaded a 300 grain bullet that was heat treated or of a very hard alloy, would the pressures be different? Would it be enough to worry about if you were near max. loads? This is a hypothetical question only.

[Ben]

Like to tell us what cartridge you'd be loading ?

If you want to be safe, If I were near max, and I changed any variable ......be it primers, brand of brass, etc. I'd drop a couple of grains and start over with my observations of pressure in the cartridge ( whatever caliber it is ? ? ? )

[Bullshop Junior]

I wouldn't think it would be enough pressure to make a difference.

[stubert]

I'm not loading for it. hypothetical thought. Eg: A jacketed bullet of the same weight as a lead bullet will develop more pressure with the same load because it is harder. I'm wondering if the same applies, going from 12 bhn to 25 bhn? in any caliber.

[dubber123]

To a point I can see what you are thinking. But in the example you give, it's only about 12 Bhn difference. A jacketed bullet is much harder. I could see maybe another 1,000 Psi., MAYBE, going from a 12 to 25 Bhn boolit. I would be surprised if you could tell a difference without pressure testing equipment. Jacketed also develop more pressure as they produce much more bore friction than a lubricated lead projectile.

[C. Latch]

If anything I'd think harder bullets would obturate less and be more likely to have gas blow-by, leading, and less pressure. That's strictly a guess.

[Doc Highwall]

If the cast bullet is .001"-.002" over groove diameter like it should be it will seal the powder gases behind the bullet, but with less force needed to engrave a cast bullet plus the fact of having lube in the grooves the pressure will be less then a jacketed bullet.

[Charlie U.]

If anything I'd think harder bullets would obturate less and be more likely to have gas blow-by, leading, and less pressure. That's strictly a guess.

I would guess the opposite. A harder cast bullet will take more to engage the rifling and get rolling, giving a bigger pressure spike.
If you have a soft lead load that is already a max load moving to a harder alloy might be risky. The safe bet would be to dial down the load and work up.

[C. Latch]

I would guess the opposite. A harder cast bullet will take more to engage the rifling and get rolling, giving a bigger pressure spike.
If you have a soft lead load that is already a max load moving to a harder alloy might be risky. The safe bet would be to dial down the load and work up.


You may be right. Stuff like this is why I don't push the ragged edge of load development.

[44man]

NO! Lead is softer then jacketed.

[grouch]

I really don't know - is more pressure produced by harder alloy, or by a riveting effect of the pressure obturating the soft bullet???
Grouch

[runfiverun]

since we are comparing lead alloy, a water dropped alloy and an air cooled alloy will be close enough [except for the bhn] that I doubt it would matter enough to worry about even at a 12 and 30 bhn, they would most likely overlap in pressure highs and lows anyway.
if we were comparing air cooled ww's and lino-type I think you might see a distinction in engraving and total pressure.
1,000 psi would probably still be an outside number between the soft alloy and the two harder ones.
that would be an average pressure jump.

[Cmm_3940]

If you want to get really picky, there is the difference in static coefficient of friction vs. dynamic coefficient of friction for any given alloy. Do you really want to go there?

[JonB_in_Glencoe]

Size...Lube...powder choice
would all be major factors in the pressure differences when comparing a boolit alloys.

[bhn22]

Lead based alloys are highly malleable. I don't believe you'll be able to notice any difference based on pressure. Accuracy, and other physical handling characteristics, yes. Pressure based? No.