View Full Version : Forming 30-40 Krag to 40-70 SS questions

08-24-2015, 09:10 PM
I have some 30-40 Krag brass that I need to form to 40-70 SS. I have about 90 cases already formed by the previous owner of the rifle. I have already blown out the case mouth to .40. Now how do I stretch the brass to 2.495 to 2.500".
Do I keep firing the brass with a media such as corn meal with about 7-10 gr of a pistol powder? Am interested in all opinions. I do not have a lathe as some suggest I need to stretch the brass with.
Also, what about the same for 303 British? I know that 303 is shorter than 30-40 krag. Interested in all opinions.

country gent
08-24-2015, 10:52 PM
How much do you need to stretch it to get to 2.500. Ideally you want to go to 2.505 - 2.510 so mouths can be trimmed square. Expanding cases up will shorten them also. Buffalo arms offers a press operated case stretcher I believe.

08-24-2015, 11:05 PM
Just use Hornady .405 cases

08-25-2015, 07:10 PM

08-25-2015, 11:22 PM
Stretching cases is a chore when you need .020 not .200.

Just buy .405 Win brass and make it work.

08-26-2015, 09:30 AM
I'd just load them and shoot them as is - they'll stretch on their own over a few firings.

I've tried to form from .405 brass, and at least for my chamber/rifle cannot make brass formed from .405 Winchester work.

08-26-2015, 10:35 AM
Thing is, recently neither Krag nor 405 brass has been available. Buffalo Arms has Krag cases to fit several versions of the 40-70 SS chamber. They are a tad short but should work well enough until Jamison gets around to making another run. I have been using BA 40-70 SS brass in a 40-70 Ballard which has a larger base diameter. I lose about 30% to case splits on first firing but after that they are reasonably hardy.

08-26-2015, 12:51 PM
Looks like Captech ( Jamison ) may have some

08-26-2015, 01:46 PM
Or you can order some 40-70 St. cases from Midway. They are made by Bertram in Aus. I got 2 boxes a few months ago and they beat the stuffin out of making my own out of anything! They are a bit pricy though, about $60.00 per box of 20 casings.