45-70 550gr project. Wildcatters and experienced loaders please comment.

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Cliff1993

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So, my project is this. I have acquired a Taylor’s and Company (Pedersoli) 1874 Sharps in 45-70. It has a 32” barrel with 1:18 twist which is rated to 29,000 psi. I would like to load the 458 SOCOM 550gr bullet from CAMPRO with smokeless powder. I have IMR 4198 and Reloader 7. There is no load data for that bullet and 45-70. I reached out to Campro and they have no data. I’ve done my research and both 4198 and R7 operate at very low pressure for the velocity I’m trying to achieve. I would like to be at around 1100 to 1250 fps. Not looking to break collar bones. All the data I have been able to find is for either cast bullets or 458 socom. Now I know people are going to say to use cast bullets and black powder but that is a project for another day. So my questions are as follows:

1. Am I sane?
2. Is this a reasonable goal to achieve with the powders I selected?
3. How would I go about finding my start load with having zero published data?

Any guidance would be great.
 
There is ample data for the 535 Gr bullet in the 45-70. Your bullet is only 15 grs heavier. Go to the starting load for 4198 and start there.....or you could reduce by 10-12% if you wish. I've done this often with custom molds in weights that data doesn't exist. I load just a few rounds, and always looking for signs of excessive pressure. I just checked my Lyman Cast bullet manual and on page 215 (1873 Springfield section) they show data for the Saeco 540 gr bullet.
The starting load is IMR 4198: 28.5 Grs for 1210 f/s & 13,500 PSI. Max is 31.5 grs IMR 4198 for 1332 f/s & 17,700 PSI.
They don't show a load for RX-7. The "accuracy" powder for that bullet is 5744. Starting load is 25.2 grs for 1096 f/s & 12,500 PSI. Max load is 28.0 grs for 1234 f/s & 17,300PSI.
Hope this helps.
 
I have that same book and I’ve seen the data. What gives me pause is the 458 socoms’s max load is 23gr of 4198. The socom has a case capacity of 61grs and 45-70 is 79. Max psi if 458 socom is 35000 well above the Sharps.
 
Cliff1993 said:
I have that same book and I’ve seen the data. What gives me pause is the 458 socoms’s max load is 23gr of 4198. The socom has a case capacity of 61grs and 45-70 is 79. Max psi if 458 socom is 35000 well above the Sharps.
Click to expand...

OK, but you're not loading for the SOCOM. You're loading for the Sharps. Different brass & different chamber. You should focus on the bullet's weight & diameter. I personally don't think you would get in trouble by using the data for the Saeco bullet and subbing your bullet and using the starting load data. I've done it many times with Pedersoli Shaps & rolling blocks, Uberti Hiwall rifles in cals 38-55, 40-65, 45-70 & 45-90
I've fired paper patched bullets in my 30-30 that weigh 190 grs, 20 grs over the available data. The .303 Savage uses a 190 gr bullet and I used that data to start. Having said that, it doesn't hurt to be cautious and I'm not advising you to do any of these suggestions but you did ask. Above all, if all this seems unsafe to you, then don't do it!
Best of luck in your quest.
 
“Best of luck in your quest”

Thank you. I think there is a very similar NOE bullet I’m going have at the data for. I’ll keep you updated.
 
I tell u what. If Campro is using the same material in your 45-70 bullets as what is used in 44 pistol bullets, be very careful on steel gongs.
Last time I shot these inside indoor range other handgun shooters complained about large chunks of my bullet ricochette.
 
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Brutus said:
I tell u what. If Campro is using the same material in your 45-70 bullets as what is used in 44 pistol bullets, be very careful on steel gongs.
Last time I shot these inside indoor range other handgun shooters complained about large chunks of my bullet ricochette.
Click to expand...
I won’t be shooting it indoors and likely at long range. So I’m not too concerned. Thanks for sharing your experience.
 
Here is some old Lyman data for heavy 45-70 bullets.

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Page 98 -Lyman 44th ED
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Page 99 -Lyman 44th ED
 
I admire those single shot 45-70s but I am at a time in my life I need a tiny bit more flexibility.
Hence my next 458 is going to be a repeater and optics friendly. Want something with equal juice to 45-90 without too much shoulder punishment.

I enjoy the easier cleaning of a bolt gun, so I am going to commit a mortal sin and ignore the lever rifle for now.
500 cast with a side of Trail Boss for dinner.
 
I have the same rifle you have Pedersoli 45-70 1874 sharps and mine loves the 500gn plus bullets sized to .460.

Lee 500 gn Varget 43.0 gn 1680 fps 1.2" at 100 meters for 5 shots.
RL-7 34.5 gn 2" at 100 meters for 15 shot group

Boomer 570 gn sized to .460
RL-7 37.5gn 2" for 15 shot group at 100 meters
IMR3031 39.5gn 2.25" for 15 shot group at 100 meters
 
All I use in the 45-70, 45-90 and 458 Win Mag is IMR-4198 for all bullet weights and from sub-sonic to shoulder punishing loads.

With that bullet, set up your chrony, start at 24.0 grs, and move up 0.5 grains at a time with groups of five until you have the accurate load at the MV you want. Pressure will still be well below 29K at 1250 fps (at about 28.0 grs).
 
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