"Small bore" Remington Rolling Block

Brutus

Brutus

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I have an antique black powder, Remington RB action. It was formerly of 45-70 or 50-70 calibre.

My question is, can this be safely rebarrelled for a 30-40 Krag or 32-40 cartridge?

Edit: A 50-90 has crossed my mind as well.
 
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30-40 krag is WAY hotter then the 45-70 of the period don't know about 32-40 but 38-40 would be OK.
30 and 32 cal would mean you gotta register it.

My choice would be 9.3x72R.
 
Recamber it to anything you want - just keep the pressures to 28k psi or lower and recognize that the gun has no gas handling provisions. You coud argue that you could go to higher pressures as the smaller diameter round produces less back-thrust and has more barrel around the chamber (and I'd agree), but for the gas-handling reasons alone, I'd keep it mild and simple - like the action.
 
The least hassle would be to rechamber to 38/55, doesn't have to be registered, and use Black Powder loads only, things change if you go with smokeless rds, and smaller cals., then you should bush the firing pin, etc.
 
Thanks guys, you have given me alot to consider.

The more I think about it, the more I'm leaning towards a big black powder cartridge that this action was initially designed around.

Cheers................

PS: Would a 50-90 calibre be to strong for this action? Myself I've never considered a 9.3 x 72R. But it's an option.....
 
more barrel around the chamber (and I'd agree),
Click to expand...

I am no engineer but the engineering literature is pretty clear that the wall thickness of a cylinder required to hold a given pressure increases greatly compared to internal diameter as you get smaller.

The walls of a 3o cal must be much thicker then the walls of a 50 cal to contain the same pressure. I know it feels nice to see thick chamber walls on small cals but they are thick for a reason. You may see paperthin walls on an old 45 but you don't see paperthin walls on many 32s. Like you say considering the lack of gas handling who cares anyway might be better off with a blown barrel directing forces all over then with a contained rupture spewing hot gas directly at your peepers.
 
The criteria that I have used when rebarrelling antique actions is to start with multiplying the pressure of the largest original round the action was chambered for times the square of the diameter. The answer is a measure of the thrust on the breach face. I compare that with the same calculation for the intended round. The issue is not pressure as such but thrust on the breach face and I/you do not want to exceed the maximum thrust that the action was potentially chambered for.
The second issue is what Tiriaq mentioned; original firing pins are much larger than modern ones and under smokeless pressures, primers can extrude into the firing pin hole around the pin and burst. You need to bush the firing pin hole and install a new pin with a diameter in the range of .075"

cheers mooncoon
 
Brutus,

I'd suggest a good look at 38-55, as about the smallest worth looking at. Mainly from the Antique perspective.

IIRC, a 30-30 case blown out to comes out a wee bit short (.045", IIRC), but they are pretty much everywhere, if you wanted to be able to save a few bucks on brass.

I have a 40-65 reamer sitting here if you want to look that way...Y'all gotta come over for a cuppa, and bring the action over too! I have a copy of Venturino's book on shooting buffalo guns, and it has a fair bit of info on at least some of the cartridges available. It's worth a read, if you can stand to read his writings.

You wanna shoot BP ? Lots more selection in the .45's for bullets.

Pretty much no limits for selection, if you are willing to search out the brass, anything from .22 WCF on up.
Bigger bore=larger surface are on base of bullet=lower pressures required to get it to move.

Cheers
Trev
 
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