Title says it all.

I just bought an Uberti 1873 Springfield Trapdoor carbine in .45-70.  It's obviously a reproduction.

I'm planning to shoot 405gr factory lead projos at about 1100 fps, just like the 1870's cavalry loads (yes I know they were black powder).

I am not planning on shooting black powder out of it, though.

I will be reloading and probably with IMR 3031.  Again, probably lead bullets, but who knows.  What is recommended?


What things do I need to know about the weapon and reloading for it?

Take 45-70 case , fill to top with black powder, compress and load 500gn bullet and enjoy. You are in the black powder forum after all

I'd ask Uberti what the pressure limits were on it and go from there.  

The reloading manuals specifically list loads specifically for Trapdoors so it's not exactly a mystery.  Quite simply you are looking to duplicate the original BP load of a 405gr bullet at around 1250fps or a 500gr bullet at about 1100fps.

That said, while it's a bit more work, shooting BP is a lot of fun and really gives a feel for the original shooting experience.

Obviously the load data is based on the original trapdoor which wasn't known for it's strength.  The modern replicas are not the same.  Only the manufacturer knows the pressure limits of their version of the gun, hence my comment.  

The Uberti trapdoors are made for them by Pedersoli.  This is right off of Pedersoli's manual for the trapdoor.

"Davide Pedersoli rifles are stronger than their original versions due in part to improved steels as well as
changes made to strengthen the original design and to add safety features. However you must always follow
the safety rules, including the use of correct charges and their maximum developed pressure"

"WARNING: IN NO CASE SHOULD THE CARTRIDGES EXCEED SUCH VALUES OR THOSE SET FOR THE SPECIFIC MODEL RECOMMENDATIONS.

CALIBERS PRESSURE:
C.U.P. / P.S.I.
.45-70 Gvt. 29007"

Well, that's a trapdoor pressure level.  The next step up is the 40,000 PSI of the 1895 Marlin loads.  The OP stated he was trying to duplicate the original 1870s cavalry loads.  He gave the parameters he wanted to meet.  Why complicate it beyond going to a reloading manual and choosing a trapdoor level load with the 3031 powder he plans on using with a 405 grain bullet?

Use 3031,  also trail boss.

Thanks.  I’m using 405 lead rn bullets with SPG lube over 34 gr 3031.

You already have bullets with BP lube (SPG), so just go ahead and burn the real deal!

Rob

Yep.  You're 90% there!  So much joy in so much smoke.  Cleaning the gun is easy.  It will just take a little more time to clean the brass.,