plain base to GC base powder conversion

[roysha]

Is there a rule of thumb for powder charge change when going from PB to GC or vice versa?

I can find lots of data for GC bullets, (this is in regard to a post I made earlier on the lever gun forum pertaining to the 1886 in 45-70) but not much for the PB bullet.

My bullet is PB so should I back off the recommended start loads, how much, use a totally different powder, or what?

I went back to my old Ideal and Lyman manuals as suggested by a poster in response to my above mentioned post and could find virtually nothing for this bullet which is the Lyman 458125 weighing 525 grains. Truthfully, I did find data for this bullet in the Ideals manuals but I no longer have any Sharpshooter or Lightning powder. :smile:

[44man]

None. Just load and test.

[chboats]

MOST of the time cast boolit accuracy falls far enough down the load pressure curve that excessive pressures are not an issue. USUALLY the boolit will fail, which will cause poor accuracy and leading, before pressures are too high for the firearm. The differencies in pressure at these lower levels for boolits of simular weight are USUALLY not worth worring about.

So, pick a load for a simular weight boolit with the powder of choice, start low and work up.


Carl

[geargnasher]

None. Just load and test.

I agree.

Gear

[white eagle]

what he said.....
really just do your normal load development
and have at it

[HARRYMPOPE]

keep velocities in the 1100-1200 fps range and you will be fine.

George

[MtGun44]

Same same.

Bill

[Bob Krack]

Plain base should cause SLIGHTLY lower pressures than gas checked and perhaps quite a bit less pressure than jacketed bullets. I personally have never been reluctant to use published loads that were for jacketed in my boolit loadings.

Most replies above are 100% correct.

Bob

[303Guy]

I'm assuming the question was meant to be powder conversions for accuracy from G/C to PB. I'm interested in this question too. It's to do with boolit base distortion and gas cutting although I've not seen any evidence of the gas check preventing gas cutting. Not saying it's not so, just that I haven't found the evidence. Actually, I've found evidence of gas cutting with gas checks - which is not proof of anything! Well, maybe it's proof of a poorly fitting boolit but that's about all.

[felix]

Gas cutting is going on no matter what. It's just dependent on when and how much when it does. Breech seating is the only way to minimize it, and to make it approach zero. Or, you can use wads the length of the freebore, or normal fillers which will fill all the chamber voids after the projectile's tail leaves the case. ... felix