45-70 advice

[coyotewillie]

Just starting to reload 45-70 for a Pedersoli 1874 Sharps. Picked up a used Cabela's model at an estate auction. Going to start out with the big ones first, but I got some cast 405g (coated), 500g (lubed lead), and some 500g (coated), .459 sized lead bullets. Acme to be specific. I bought 2 boxes of factory cartridges (jacketed bullets) just for something to shoot to get the feel of the rifle and to have some brass...no problems with shooting/grouping. Reloaded some 500g both lead and coated. So today I shot 20 rds of the lead and 10 rds of the coated. The lead was all over the place...and I mean shotgun spread. Literally only 2 rds out of 6 on a 4x4 sheet paper at 100. And, it looked like those 2 keyholed.

I went to the coated 500's and I immediately got a cluster. Was adjusting my new vernier sight and brought it right into center of the paper. I shot the last 2 rds without sight adjustment and they were an inch apart. Wish I would have had at least a couple more to verify but, oh well for now. I honestly feel the coated are going to hold a group. But why such a HUGH difference??

I went with .459 size because it seemed like the majority of Pedersoli sharps shooters I read about thought .459's shot better than .458's in their rifles. So I figured I'd try them first. I reloaded for years, from 17FB to 338Lapua, but never reloaded/shot any cast lead. Now, I've done a bunch of reading on reloading 45-70 for these rifles but I don't recall reading about this bad of lubed lead results! So...any ideas on what's going on here?

 

[mgunderson]

I expect the lead was a little soft on the bullets that didn't shoot well. This is not my normal wheel house, but gas checks and paper patching were developed to help the lead survive in the rifling.

What coating is on the bullets that work. I expect they are harder or the coating it helping it survive in the rifling.

The book 40 years with the 45 70 is a fun quick read.

 

[tharger]

I had a pedersoli sharps. Only shot lead. Oh yes. Black powder. The real stuff. Shot really well

 

[Brian.Egeberg64]

It’s likely a sizing issue between soft lead bullets and harder coated bullets. Measure them to see what I mean, it may only be .001 or .002 difference.

Did the pure lead ones leave a lot of lead in the barrel, silver grey streaks? Undersize can be bad too! You may want to slug it for size.

I cast for many calibers and find a harder cast bullet stand up way better once you get over 1,000 fps in velocity.

 

[JSH]

Go to black powder and smile.

 

[spencerhenry]

Do you mean powder coated? The coating probably increased the size of the bullet. .459 seems on the smaller side especially if the bullet is really soft.

I cast some pretty soft lead bullets for my .405 winchester, they come out of the mold .413 to .414, I tumble lube them as cast. Theoretically .411 is the proper diameter. I am not running them fast. Killed a cow elk with one, bullet is so soft about half of the bullet was eroded away.

I'd guess bullet is not being stabilized because it doesn't engage the rifling properly. As in too small.

 

[Doug Casner]

Watch that Acme stuff. The coyote never had much luck with it. Doug

 

[dantiff2]

Your results are typical for bullets that need to go up (bigger) in diameter. I'd start at .460" as a minimum diameter and work up. I had a 308 diameter barrel do the same thing and did not start grouping cast bullets well until I worked open a sizer die to .3115. 1000% improvement in grouping vs a .309 diameter. Do not crimp the case mouth. That will cause under-sizing and damage to the bullet also causing poor results. Neck tension is another issue. with 460-462 dia bullets, you do not want more than 2 thou neck tension at the most or you will deform the cast. you may need a different mandrel to get appropriate neck tension. I shoot for no more than .002 with lead bullets. Also, try a lighter bullet. 405gn may be on the heavy side with your rifles twist rate. I don't know what you have but measure it and let us know the twist for better help.

Edit to add, Don't get too caught up in the one to two thou over bore with cast. It's a good starting point. I have a particular 9mm pcc with a .3555 bore but will not shoot .356 or .357 cast very well at all (6-8" groups at 50 yards) so for craps, I loaded them up straight out of powercoat and not sized down at all. These can range anywhere from .358 to .360 diameter and they shoot great! Since they are cast lead-there's no increase in pressure.
Dan