.45-70 "Artillery" 500gr load testing

So this post maybe should of been titled "Should have brought a 45-120". But anyway, decided recently to try casting my own bullets. Primarily as I wanted 500gr projectiles for my 45-70 1874 Sharps replica. Cast in was is essentially pure lead. Such a big hunk of lead it feels a bit like loading an artillery shell into my rifle.

So I'm on round two of trialling a black powder load for this projectile. I'm using 70gr of FFG holy smoke. Uncompressed this load almost fills the case so to fit the projectile you need almost 0.7" of compression.

First round of trial was OK. Good velocity (same velocity as the 405gr with 60gr of FFG at about 1260FPS) and no leading in the bore I could find or see from the soft lead projectile. Velocities were also very consistent (less that 60FPS variation between 8 shots). So it was good to see the cartridge seems to respond well to a very compressed powder column.
Decent accuracy and velocity but hard to chamber.

Cartridges were hard to chamber as I had deformed the projectiles when seating. So they were jamming into the throat of the chamber.
I hadn't allowed enough room in the case to seat the projectiles fully and they were being deformed to over calibre diameter. Chambering required a bit of force to close the action. No big deal or safety concern for a soft lead and black powder load but two I couldn't push in far enough to chamber.
My mistake was trying to use the projectile to compress the last little bit of the powder column which I often do with lesser compressed loads and harder projectiles.

I also found the lube I was using which was given to me and might be as old as I am was not keeping the fouling soft at all. So accuracy suffered if not cleaning between each shot. Normally with SPG lube I can get 3-5 before noticing any change. A 32" barrel does somewhat seem to be prone to hard fouling at the end of the barrel the lube runs out. Might have to try a lubed felt wad or something but it's so hard to source things like this in NZ.

This time I used my powder compression die to compress to the final compression and then seated the projectiles exactly to this depth so the projectile just stops on the card wad.

A few snaps of the process:
Powder before compression (no drop tube, just poured in).
Attachment 217559

Card wad (home made) using a wad punch on my press.
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Projectile. I hand lubed these with the NZ made black powder lube https://www.beavergrease.co.nz/. Messy business and I'm not sizing these projectiles as they are bang on the size I want so I get excess lube all over the case and seating die on seating. Nothing a bit of paper towels and rubbing alcohol won't clean up though.
Attachment 217561

Seating depth ideally shooting for 0.69" into the case.
Attachment 217562

Powder column compressed to just over 0.69" from case mouth. The maybe a few thou space between the card wad and projectile but not enough to have any issue at all.
Attachment 217563

Powder compression dies, which consists of a powder compression plug inside a a Lyman decapping die I've modified for the purpose.
Attachment 217564

All loaded up ready for testing. A very light factory crimp die crimp to remove the flare on the case is used (you can also see the marks this leaves on the cases from previous firings).
Attachment 217565
Attachment 217558

they boot a bit more too.....

Yes, I certainly noticed an increase in recoil. Just adds to the fun of course.
Entirely tolerable in a rifle that weighs 5.1kg.
Attachment 217677

Love the rifle, I've got the capping breech loader version and probably should have gone cartridge anyhow. With the powder compression die you will be breaking some of the grains, up you could try 3f if you can get it that would give enough room for a grease wad. You have a wad cutter so if you can get felt it will cut that. I make mine from old pairs of shearing moccasins they're partly greased already but I still float then in melted lard, hook them out and let them harden.

OK so if Ive got my head around this correctly,all black powder is pretty much the same stuff but its graded/sieved to give the f ff fff grade????
and what your suggesting is use WEIGHED charge of finer powder to fit it in case better...sort of like using a ball rather than stick powder for same reason VS a stick instead of ball to fill case up more....... have I got that right???

Zegactly.

eggzachary........OK that will tweak my interest if I get around to digging it out of cabinet again....

Always wondered what the bc of that projectile might be compared to the hornady monoplex. These aren't gas checked eh. Not that you'd really ever need to tbh. I've dug enough 350gn pc bullets out of the clay to believe that you're good to push to 1800fts easy with no GC.