45/70 Pyrodex FFG problem

[roundgunner]

A friend asked me to make him some 400 gr RF with 60-65 gr of RS=FFG Pyrodex he dropped off. I can’t get that much in the case. I did 20 rounds with 45 gr but the load data said 60-65 should fit. What gives?
It is for a Springfield trap door.

 

[John R]

That should be a compressed load, and it should fit in the case.
Are you weighing it on a scale, or are you using a dipper?

 

[roundgunner]

Should I be packing it down with a sharpie or something? seems like a PIB

 

[SMSgt]

The .45-70 was designed for 70 grains of black powder. I don't think they had Pyrodex in mind back then.

 

[roundgunner]

So is the BP smaller volume?

 

[venomballistics]

Should I be packing it down with a sharpie or something? seems like a PIB

They sell brass drop tubes for this sort of thing.

 

[Photog]

You also have to remember that many of the early 45-70 cases were "balloon" head cases, and thinner brass, especially through the web of the case, so therefore had a greater capacity.

 

[Fishinfool]

I have never loaded black powder, or its substitutes, in cases, only in muzzle loaders. BUT - black powder, and Pyrodex, at least in muzzle loaders, is supposed to be loaded by volume, not weight on a scale. That may be the problem?

Larry

 

[alwslate]

Pyrodex equivalent BP loads should be measured by volume not weight.
Read Hodgdon's information on the relationship between the two.
65 grs of Pyrodex by the scale will be equal to a much larger charge of
BP. Set a BP measure at 65 grs, fill it level full with Pyro and charge
case.

 

[Ivan the Butcher]

+1 on volume measuring! That should still be a full case. You may need to use a drop tube. Without a compressing die hand compressing get inconsistent. Have at least a medium crimp to keep the bullet from "creeping" out of the case. I prefer real Black Powder to any of the subs, but especially Pyrodex! Ivan

 

[scooter123]

A while back I read an article on re-creating classic old black powder loads using Black Powder, the real stuff. In the case of the 45-70 getting a 70 grain charge into an actual antique case required that the charge be HEAVILY compressed, so hard that it could only be done in a separate stage. They had to fit a fabricated ram into the die carrier in the press, fill the case, and basically compress the powder charge so that it was pretty much a solid. Then the 405 grain bullet would fit. As for the reason the charge was compressed so heavily, theory in the article was that doing this slowed the burn rate of the powder. Since Richard Lee mentions compressing smokeless powder loads to slow burn rate in the Lee 2nd I can only conclude that the same would be true with Black Powder.

 

[Bart45]

I have two Sharps rifles in 45-70 that will never see a black powder substitute..........

 

[Pisgah]

Hodgdon recommends enough Pyrodex to fill the case so that LIGHT compression is needed to seat the bullet. No weights given -- it's all volume.

 

[roundgunner]

Well that is good news, I did fill high enough to have the bullet compress it about 3/16 ". I hope it works out for him but I would rather deal with smokeless. Any body use light loads of smokeless?

 

[Nick B]

I shoot lots of Goex black powder in 45-70 and 45-90 . You have to use a drop tube to trickle the powder into the case . Mine is 24" long .
For 45-70 you need to compress it about 1/8" and use a soft bullet with a lube designed for black powder .
In a modern 45-70 case I get about 64-65 grains in when using a 410 grain bullet .

 

[MichiganScott]

After you figure out which volume of Pyrodex equals 60-65 grains by weight of blackpowder, make certain that you use a brass or aluminum measure for the Pyrodex that is designed for blackpowder. Using a measure designed for smokeless when reloading black can lead to a very unpleasant surprise.

 

[LoboGunLeather]

Well that is good news, I did fill high enough to have the bullet compress it about 3/16 ". I hope it works out for him but I would rather deal with smokeless. Any body use light loads of smokeless?

My light smokeless load for .45-70 is the Lee 458-340 RNF cast bullet over 30 grains IMR 4198, standard large rifle primer. About 1350 FPS, quite comfortable to shoot in the Trapdoor rifle or carbine, and very effective on game animals.

Original loadings included two standard cartridges. For the rifle it was 500 grain lead bullet and 70 grains Ffg, hence the common cartridge designation as .45-70. For carbine the standard was 405 grain lead bullet and 55 grains Ffg, referred to as the .45-55.

As others have noted, the actual loading of 70 grains of Ffg in the .45-70 cartridge requires quite a bit of compression, especially in modern solid-head cases. Even 60 grains will usually require bullet seating in 3 or more stages, allowing some time between for the powder to compact sufficiently to proceed.

I have not tried Pyrodex in this cartridge. If I were to do so I would probably stick with the 55 grains-equivalent of the carbine loading as a maximum, which by volume measurement would weight about 48 or 49 grains in Pyrodex. Heavy charges, especially with heavy bullets, in the .45-70 can be very uncomfortable to shoot, and the old Trapdoor Springfields are not known for the strength of their actions. Also, much reduced loads with black powder (or substitutes) that leave air space in the loaded cartridge are not a good idea; these powders should be used only with the projectile seated firmly over the charge.