Friday, May 01, 2009

Flintlock Tom

Flintlock Tom asks in comments:
I'm just getting into the .45-70. I just picked up a Springfield Trapdoor made in 1891. I would like to develop a black powder load, and, eventually, a light smokeless powder load. However, the bullet size has me puzzled. I slugged the barrel and it came out around .456-.458, but the Lee mold I have ordered says it throws a 405 grain .459 bullet, with a hollow base. Would an "over-sized" lead bullet like that cause pressure problems? Also, I see that some people use some kind of "wadding" over the powder, what's the purpose of that.

Thanks for your help.

Flintlock Tom
I'm glad you asked, Tom. Lets see if we can answer some of your questions.

Cast bullets for black powder loads in the .45-70 need to be one-thousandth oversize. I routinely cast bullets at 0.459 for my .45-70. That's standard. Heck, I size cast bullets at 0.309 for my .30-30 and at 0.358 for my .38 Special. It's not going to hurt a thing, and it will actually help. If the bullet is undersize by even a fraction of a thousandth, hot gasses will escape past the bullet, cutting the bullet like a torch and depositing lead ahead of the bullet. The bullet, in passing, will iron it into the bore. Having a bullet one-thousandth oversize is good practice.

I use pillow dacron stuffing over small charges of rifle powder in the .45-70. For example, my load for the .45-70 calls for 2.5 cc of IMR 4895, which doesn't come near filling the case. I take a tiny pinch of dacron stuffing and put it over the powder with a pencil eraser. It promptly expands to fill the case, then I seat the bullet over the top of the stuffing. The dacron holds the powder against the base of the case, near the primer. This is standard practice for large straight-wall cases and reloaders have used any number of fillers, to include Cream of Wheat. Having the powder near the primer helps the powder "light up" consistently.

Don't use fillers with bottlenecked cases because the filler will compress when going through the case neck and might cause an obsrtuction, leading to a high-pressure excursion.

For loading black powder, Junior has put together a great tutorial. Click on the link for the article. One thing to remember, and also good practice, is to include a grease cookie between the ball and the powder when using black. That's an old-time trick that helps accuracy and helps keep the fouling soft.

One other thing to note is that the trapdoor action is not as robust as modern rifles in .45-70. The loads you use will need to be low-pressure. Most good reloading manuals break the data down into three sets; one for trapdoor, one for lever actions, and one for Ruger #1 and other modern falling blocks. Use data appropriate for your action type.

Enjoy your trapdoor.

3 comments:

Anonymous said...

Thanks for the info and the link. I'll let you know how she shoots when I finally get all my ducks in a row.

Flintlock Tom

JPG said...

Interesting info. I realize how convenient it is to use a dipper for loading, but not having a full set of Lee dippers, I can't relate to "2.5 cc of IMR 4895." Can you say what grain weight that volume equals?

I have a satisfactory load for my Marlin 1895GS with IMR 3031 and 400/405 gr JSPs. I'd like to try a milder load or two, and if your 4895 + 405 cast formula works well in a Trapdoor, it should be a nice lower-end combo for my lever gun.

I don't think I'll get back into casting, but I should be able to find some of the 405 lead for sale someplace.
Best,
JPG

Flintlock Tom said...

JPG,
Both MidwayUSA.com and GeorgiaArms have 405, .45-70 cast bullets for sale.