I have 2 molds for the 45-70 the 500grain one and a 300 grain one if I remember correctly only the 500 grain one has the gas check design..
As I said I'm new to this calibre so still fumbling about until I get what I need to work in the rifle and seen on you tube people were powder coating 45-70 lead bullets to prevent leading of the barrels, never powder coated before so this was also new but actually a very easy process.
I also have a martini henry that I cast for but I don't powder coat those..
My 405 gr mould is not gas checked either.
Actually I've never owned a 45-70 myself. I picked up the mould, a set of dies, and a Lee push through sizer second hand at the Phoenix arms fair on a whim (ISTR I paid £40 altogether for the bundle), having it in mind to maybe buy a rifle one day.
I was already casting for several other calibres (including 30-30, for my Marlin 336), so ran off about 100 bullets to check out the mould, which a club member was interested in trying in his Marlin. Otherwise they'd have been re-melted for something else.
Pan lubed, and pushed through the Lee sizer from the base (no top punch needed with the Lee push through sizers). First sized without lube, then pan lubed, then the excess lube scraped off by pushing them into a fired 45-70 case, the head drilled out to insert a rod to push them back out again.
We loaded them up just taking average data halfway between start and max. for the 420gr listed (naughty I know) from the Lyman Cast Bullet Handbook.
Bullet seated and crimped at the topmost lube groove.
The plinking load with Unique, which was a lot of fun to shoot, and the full load with Reloder 7, both of which powders I already had. When we shot the full loads I found them very stout, my first experience of a full 45-70 load. They shot quite well and didn't seem to create any significant leading with the dubious lead alloy (recycled range scrap), probably shot 30 or 40 of each that session.
I decided that another Marlin was a bit superfluous for me, already having the 30-30, which I thought had greater range and accuracy potential, as well as using a lot less lead (165gr). Also potentially a useful deer rifle, it can make the numbers for all deer in England/Wales. Not so much use in Scotland though.
I am interested in trying powder coating, what powder did you use, and how did you apply it ?
Yes but they were pushed really far back into the case so obviously worried about pressure ..taking a dummy round to the range today to consult with some guys that have more experience than I do
PS: since you say you are having to seat those 500gr bullets deep, are you going to be able to put a crimp on them ? The Lyman loads for lever action Marlin and Winchesters are all 2.550" max. COAL. which is the standard max. COAL for 45-70, Which I presume the 1895 lifter and ejection port are dimensioned to accept.
You can load longer in things like Sharps
FWIW on my 336 it was dimensioned to only just take 30-30 made to the max COAL. Any longer and it couldn't eject loaded rounds (don't ask me how I know). Embarrassing, had to take off the lever and pull the bolt further back to wiggle it out.
So if that bullet was designed for 45-70 it ought to be possible to crimp into the top lube groove and still meet that COAL. However if not (and looking at your photo maybe not) you would have to crimp somewhere on the smooth portion. Maybe a Lee Factory Crimp die could do that satisfactorily, forcing in a cannelure, just a thought. Or maybe your standard seating die can still put a decent roll crimp into a lead bullet.
If you can't put a good roll crimp on them, then I'd suggest you only single load. Otherwise in the magazine tube you might certainly expect bullets to get pushed further into the cases under recoil, particularly in a 45-70 shooting very heavy bullets with very stout recoil. Which could be disastrous.
Not sure where you might find any precise load data for that combination either, I suppose a candidate for doing some simulation to try out some ideas.
Might also be worth studying
Official 500 Grain 45-70 Load Data questionnaire for Marlin and Winchester Leverguns for some mixed opinions on the merits of trying to shoot 500gr bullets from a levergun.