.45-70 Cartridge Length Question

[broken-mold]

I am going to start reloading some light loads for my Trapdoors, H & R Buff Classic, and '74 Sharps. Some manuals recommend 2.095" trim-to length for the brass, some recommend 2.100", and one recommendation I read was to cast the chamber and trim the brass accordingly.
I have new Rem brass and most of the fifty rounds mic to 2.094"- 2.095. Will the brass grow to 2.100" or more even when using light loads?
I have some older brass that mics to about 2.092"-2.093". What is the drawback of using brass a thousandth or two under the recommended length?

[elmacgyver0]

Zero to none.

[Randy Bohannon]

Trim to the shortest piece so their uniform in length and go shoot. Deburr inside and outside before loading.

[2TM101]

Thats not the cartridge length you need to be concerned about.

If you get ahold of any Hornaday "Leverrevolution" stuff it will be considerably shorter than standard, and if your dies are set for the real thing, like a Starline case, it won't crimp. Regular dies can't even be adjusted down far enough to do it. I got really frustrated by that until I found out their cases are shorter because of the bullets they originally come loaded with (???) and learned that - I can't crimp them at all.

Allis not lost as they can still be used in single shots. And leverrevolution 45-70 tends to be relatively cheap on Gunbroker as people with repeaters can't use them (without a lot of work). As I have a one shot CVA Scout I can still use those and I make them up as my .45-55 rounds. As a CVA Scout is a really light rifle the normal rounds really kick - and that's why the 45-55 existed in the first place.

[country gent]

In my single shots I dont crimp just take the flare off any off.I trim close to chamber length ( saves the chance of getting a lead ring there) Load just off the rifling. Most of my loads the bullets can be seated by hand onto the wad stack and compressed powder charge.

Your brass will grow but at BP pressures and velocities it will be slow. Your brass will work harden from sizing and expanding you want to anneal it. this gives a better seal and more consistent tension. Chamfer and deburring only needs to be done after trimming. Deburring flash holes can make a difference in accuracy.

[Bent Ramrod]

For grease groove boolits, the standard trim-to-length in the books (~0.005” shorter than nominal length) is fine. Your 2.095” brass is right in there.

For paper patched boolits, 2.095” is about as short as I want to see brass; 2.099”-2.100” is what I have my trimmer set for, for my .45-2.1s.

Using grease groove boolits, the shells shouldn’t lengthen, unless you leave the chamber wet after wiping. I find that paper patching tends to lengthen brass. Lubricating the inside of the shell neck with graphite or Motor Mica reduces this tendency, but doesn’t entirely eliminate it.

A chamber cast, properly measured, would positively let you know how far you could let the shells lengthen, but I myself would only make the effort if something about the shooting was off, accuracy-wise, or if it was one of the more notorious oddball chambers, like on some Sile replicas, or early Farmingdale Sharps.

[Gunlaker]

You probably will never need to trim that brass. After you shoot it, the brass will swell to the dimensions of the chamber and shorten a bit more. In a lever gun with hot loads you'll find the brass stretching to some degree, but in a black powder single shot you'll get very little to zero growth. The only time mine grows is if the chamber is a little wet, and even then, more so on the longer cartridges than the 45-70.

Chris.

[1Hawkeye]

I agree with the others and I'll pass on a tip about the hornady brass while being too short for a .45-70 it works great when sized down to a .40-65 with very little excess to trim off.