Breech fouling in 45-60

[Win 1876]

I am new to black powder reloading but not to reloading in general. This is the first BP load I have developed. This is my first post so if I need to post elsewhere please let me know.
First some info on the rifle and load.

Rifle: Uberti reproduction of a Winchester 1876 (Tom Horn)
Caliber: 45-60
Oil: Ballistol
Barrel cleaner: 1:7 ballistic : water)
Barrel diameter (slugged): .456

Ammunition
Bullet: lee 340gr .458"
Lube: 1:1 crisco:beeswax
Case : trimmed starline 45-70, annealed after trimming.
Case length: 1.826"
Powder: 55gr Old E 1.5F
Compression: .0885"
COAL: 2.25"
Crimp: yes
RCBS 45-60 dies

With this load I am getting an original 3-shot group of 2.5" at 50yds. With no cleaning a 6-shot group opens up to 8" at 50yds. With cleaning after 3 shots groups remain small. After shooting and zeroing for the day I fired 3 more shots and went home without cleaning the rifle. Once home I bore scoped the barrel and found very light fouling for the muzzle and center of the barrel. The 2.5" nearest to the breech (from the start of the rifling 2.5" in) had a hard fouling that chipped off in sheets with cleaning. I have read extensively on muzzle fouling due to lack of lubrication. I have not read about breech end fouling or how to fix it. Any advice on how to fix the issue? If possible I would like to shoot my repeating rifle accurately as a repeater.

~ pictures are of 12" from the muzzle and 26" from the muzzle.

-Win 1876

[Dave T]

In reading your report three possible problems come to mind.

First, you bullet isn't carrying enough lubricant.  A better designed bullet might help.  Also a card wad seated on the powder charge, followed by a lube soaked felt wad, then store the loaded ammunition nose down until ready to shoot.

Second, you may need a better lubricant.  To eliminate guess work, use something that is tried and proven - like SPG - until you sort out the fouling problem.

Third, you didn't say what alloy your bullets are cast from. If it's too hard and doesn't upset in the forcing cone it can lead to all sorts of problems.  Most BP rifle shooters recommend no harder than 20-1, lead to tin.

No guarantees any of this will solve the problems your having but it's somewhere to start.

Good luck,
Dave

[Win 1876]

 Thanks for the recommendations Dave!
My alloy is pure wheel weights soft cast (no quench) they deform readily if dropped from table height so are at least a little soft. Due to the COAL constraints of the platform (2.25") I was trying not to have to add wads due to decreased powder capacity. This round will be used for hunting so velocity is an important factor. What thickness of wads would you recommend? Do you have a bullet that you would recommend with a better BP design? If possible I would like a 300gr bullet to better approximate the original loading.  I had the 340gr on hand for another project so it is not ideal.

[Dave T]

I don't think Wheel weights are a good choice.  I used to shoot Magnums (357s & 44s) with wheel weight bullets.  The Ordnance  Dept used 1-16 in their 45-70s but I've read a number of times Winchester used 1-20 alloy back in the black powder cartridge days.

As to a bullet, I'd recommend you look into Big Lube's 320g 45-60.  Mark Whyte (www.WhyteLeatherWorks.com) casts them from 1-20 alloy and lubes them with SPG.

If you get a bullet carrying enough of the proper lube you probably won't need any wads.

Dave

[Win 1876]

I am a little confused when it comes to bullet casting alloys for black powder. In the Lyman handbook the BHN for wheel weights is ~9. The BHN for 20-1 is ~10. This means that 20-1 is harder than wheel weights? The 20-1 has no antimony while wheel weights have ~4% antimony.  What attribute makes wheel weights not suitable for mid range black powder cartridge reloading?

-Win 1876

[David Battersby]

.........In the Lyman handbook the BHN for wheel weights is ~9. The BHN for 20-1 is ~10. This means that 20-1 is harder than wheel weights?.......

-Win 1876

The wheel weight alloy that I have been making for the past 10-12 years has always checked around a BHN of 14.  This is almost hardball . a 20-1 alloy will obturate much better. This should improve accuracy and may help with the breech end fouling.    I have experienced hard fouling just ahead of the chamber using Swiss Black Powder.  I shoot 44WCF and 45-70Gov't in lever guns. The cure for both of the times this has occurred is using a "softer" (colder) primer. In the 44WCF (44-40) is was using Winchester Large Pistol primers as I had a lot of them. These primers are hotter than standard primers but cooler than magnum. Switching to CCI 300 primers , at the suggestion of John Kort, cured the fouling issue and increased accuracy.  You may want to try the same load with a softer bullet and different/softer primer.   If using a Magnum Rifle primer, try a standard rifle primer, if you are using a standard rifle primer then try a standard pistol primer.
Figuring out a black powder load can be a little frustrating , but when you find it the reward is great.

[Win 1876]

 Thanks to everyone for their input. I will try changing variables such as alloy, lube,  and primer and will post back my results just in case someone had the same problem in the future.

-win 1876