New BP Shooter, 40-70 BN Question

[R.E.Lee]

Hello All,

I’m a long time gun enthusiast, new guy at re-loading in general, specifically I’m interested in loading BP cartridges.

In the last year, I have bought several BP guns with different chamberings. I have been able to source some ammo in various places, but I recently bought a nice, original Sharps chambered in 40-70 Bottleneck. I know Buffalo Arms offers rounds in the caliber, but I called last week and they told me to “move on to my next project” it would be so long before they re-stocked that ammo. Even when it’s in stock, it’s over $110 for 20 rounds.

I understand some of the basics of re-loading and have Lyman’s Black Powder Handbook, which I’m still reading.

I’d like to load some 40-70 BN cases for my rifle. My first problem is finding the brass. RCC makes custom BN cases at $5.00 a case. As far as I can see, that’s the only source. Is there a way to form the cases correctly from another brass case? If so, what is involved in that (granted I have the correct case dimensions to work with). I have seen some info on forming the straight walled case from other brass, but I’m unsure of how to form a BN cartridge.

The second issue is the die sets. I can only find custom order die sets for the BN cartridge. They are very expensive and 1 year + wait time. This may be a stupid question, but if we are talking about unfired, new brass, is hand seating going to be impossible? Are there universal tools that I can buy that will help me complete this project?

I understand that after the case is fire-formed I may be able to hand-seat the bullet. I’m mostly interested in what tools I may need to re-size the case or add neck tension or crimp the bullet without die sets.

Besides these question, I have learned a lot from reading these posts. I think I have most of the other gaps filled.

I greatly appreciate the advice and guidance everyone.

R.E.Lee

[semtav]

If the parent case for the 40-70 bn is a 45-70, like the 40-50 bn, there are ways to Bottleneck the case without the proper sizing dies. Do you have 40-65 dies?

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[Don McDowell]

Run a 45-70 case into a 40-65 die and fire form

[MichaelR]

You will need to use 45-90 brass to form cases. The 40-70 case should be 2 1/4”long. You need to measure the bore diameter for paper patched bullets unless someone has altered the chamber for groove diameter bullets.

[R.E.Lee]

If the parent case for the 40-70 bn is a 45-70, like the 40-50 bn, there are ways to Bottleneck the case without the proper sizing dies. Do you have 40-65 dies?

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Thank you for the reply.

Lyman makes a die set they say is 40-65/40-70 straight. I’m assuming I’ll want to anneal the brass before I run it through the smaller die to form the case?

[ndnchf]

I shoot a .40-70BN Shiloh Sharps. If you find the parent brass, I could run them through my dies for you.

[Randy Bohannon]

What a nice gesture ndchf, good people here for sure.

[R.E.Lee]

What a nice gesture ndchf, good people here for sure.

Indeed! I sent ndchf a PM to take up his generous offer.

[wwmartin]

40-70SBN and 40-70straight are not the same cartridges.
You make the bottle neck brass from 45-90 and trim to length. Dies show up on ebay every once and a while. I neck size my 40-90SBN with a 41 magnum die.
Bill

[kootne]

The 40/70 BN is a 2-1/4" case. The easiest parent brass is 45/90 which is 2.4". The rims will probably be thinner than they should be but can be swaged forward with dies you will have to make yourself. If you don't swage the rims, seat your bullet out into the rifling to hold the case head back against the breechblock and hopefully fireforming the shoulder as far forward as possible. That will minimize the potential excessive headspace. if you don't full length resize (and there is no need to as long as the fired cases will rechamber) you don't need to seat the bullets out in loads after that. The 40/65 die trick mentioned above works well, I made many that way. just don't size any more than necessary to chamber the case.
If, as you say, you are new to reloading, loading shells for an obsolete caliber in an antique rifle has lots of considerations. For safety sake, I would encourage using black instead of smokeless powder.