Good afternoon all,

First time posting here! Please let me know if this is the wrong place.

I’m a newbie to the world of BPCR, but I’ve managed to collect a few rifles recently that are in good, shootable condition, and I would like to start loading for them. I’m starting with 50-70, since I have a Springfield 1866 and Sharps 1863/68 carbine. I’ve slugged the bore, and they both are around ~515ish. I bought a Lyman 50-70 die set, but it seems to be designed for 512 bullets. I want to cast and shoot 515 bullets, and based on my research that I need an older set of dies. It seems at some point, molds and dies went from 515 to 512? 

Any help would be greatly appreciated. I’m too new to post in the buy/sell/trade section of the forum

Thanks everyone!

Sincerely,
squeakie

All but one of my 50-70s are originals.  My "standard" load is 67 grains of FFg, 450g Lyman 515141 bullet lubed with SPG lube, and Federal 210 or CCI 250 primer.  Same load works reasonably well in Sharps conversion carbine, New York rolling block carbine, side hammer Peabody carbine, and a Springfield USN 1870 rifle that I have.  Your 1866 Springfield and the Sharps carbine probably both have more or less the same barrel since Springfield did the sleeving on the Sharps carbine barrels.

I am also working with a reduced load of 60 grains FFg and a 350 grain bullet (Lyman 515139) which has a lot less recoil than the standard load.

My dies are RCBS and I've never checked to see what they are designed for specifically.   I generally use a light crimp because of using the same loads in different rifles.

Originals probably won't be target rifles, but they are a heck of a lot more fun to shoot.

George

Squeakie wrote on Aug 29^th, 2025 at 1:50pm:


Squeakie,
Once you fireform your cases you will only need to neck size the brass to load them, if you are using them in only one rifle.  You can back out the sizing die to do this.  You can get a larger expander and compression plug from BACO that should fit in your Lyman die, but call them first to make sure.  If you are going to use 20-1 alloy, the .512 bullets should bump up to the groove diameter.  I have a Hoch .459 and it shoots fine in my TD that has a .462 groove diameter.

Cheers,
Steve

My Lee mold drops bullets at .517 - .518, my 1863 1st Conversion Sharps in 50-70 slugs the bore at .515. The Lee push through sizer is spec'd at .510, so not a good combination, a .510 bullet down a .515 bore in my opinion. To make a sizer, I used an extra Lee powder through die and bored it out on the old South Bend 9" lathe just to get it rifle up and shooting. Eventually, I will bore out a Lee push through sizer to .515 -.516. 

I guess my point is, you may have to get a sizer made or make one yourself, if your mold drops bullets to large to just shoot  Someone on another forum made his sizer from a 7/8 x 14 bolt. I just had an extra die from a box of odds and ends.

Thanks so much everyone!  I really appreciate the help. So I now have 3 bullet molds (Lyman 515141, 515139, and Lee 515-450) and .512 and .515 sizing dies for a Lyman 4500. Bought a new Lyman 50-70 die set, an old RCBS 50-70 die set, and a custom 515 expander and compression die from buffalo arms. Also got a neck sizing die from CH tool.

I've never developed a load for a gun like this before, and I've got alot of variables here, so any advice for building up a load would be great. I picked up a copy of Roy Marcot's 50-70 Shooters handbook (expensive$$$) and will read through it. Things that I am trying to figure out:

-Alloy
-Power charge
-crimp vs no crimp
-bullet size
-seating depth 

Once I have some free time, I will build some test groups and get to work. Ideally I want a load that works reasonably well in both rifles, and any future 50-70 rifles. I really really want to get my hands on a nice 50 cal rolling block!

Will post my next steps, stay tuned!

squeakie