Loading for the .43 Spanish rolling block

The Goose

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I recently wrote up a post on the Milsurp Forum on this rifle, a Uruguayan Artillery Short Rifle in .43 made under license to Remington by Auguste Francotte of Leige, Belgium. So if you are interested you can go there for more info.

Let me start by saying that I screwed up on this one. I slugged the bore of this rifle and did a chamber cast, however the chamber cast was sloppy and I did not want to repeat it so I made some assumptions. We all know how that tends to work out.

The groove diameter of the bore is .439. I cast up some 370 gr. RN bullets from some nice 1:40 alloy that I had from Rotometals in a Lyman mold. I ladle poured the bullets. They fell out of the mold at .442 and I sized them in a .439 sizing die, but actual was .440 which is what I was looking for. I lubed with SPG black powder lube.





I managed to acquire 20 pieces of .43 Spanish brass @ $3.30 each. Wow! I used Lee dies with an RCBS #22 shellholder. The Lee shellholder did not work on this brass. I used a large magnum rifle primer and 70 grs of Swiss 1.5 black powder, a .030 Walters wad with some slight compression. Powder was poured down an 18" drop tube.



I hit the range and fired off my 20 rds. The bore was cleaned every 5 rds. Here is the results at 50 yards with a 12" target and new cardboard. Quite a group.



When I examined the fired brass this is what I found.



The bottleneck had blown out and it was essentially a straight walled case albeit tapered. I measured the inside of the case neck and got .454. The rifle had been converted from .43 Spanish (a bottle necked case) to .43 Reformado. When I got home I slugged the bore twice more just to double check and it is definitely .439. So this rifle was converted from .43 Spanish (.439) to .43 Reformado (.454), but the bore was never changed. This was not uncommon by the way. Regardless, it does present a challenge for the reloader.

.43 Reformado brass is next to impossible to find, however, regular .43 Spanish brass can just be fire formed (which is obviously what I did). So what the heck do I do from here on? I am not going to re-barrel or re-bore the rifle. I did a google search and came up with a half dozen suggestions, some quite exotic. This is what I am going to try;

The bullet is sized correctly. I suspect that the all over the place accuracy is from the jump in the oversized chamber. Full resizing is out of the question. It would way overwork the brass. Imagine going from a .439 bottleneck to .454 straight walled repeatedly, that is a lot of fluctuation in the brass. I am going to experiment with seating the bullet out as far as possible so that it actually contacts the rifling, but will still chamber. One of the beauties of black powder is that bullet seating depth does not change pressure as long as the base of the bullet is slightly compressing the charge. So either more powder, a filler, or wads or grease cookies could fill any extra space. Since the rifle is a single shot I only need minimal neck tension to keep the bullet from falling out. I am sure that I have any number of dies that would just kiss the neck enough to hold the bullet in place. This way I m not overly working the brass. I may also experiment with a paper patched bullet. I will keep you guys informed on future progress. Your thoughts are welcome.
 
I would say find a straight-wall cartridge with the required diameter, buy the sizing die for that cartridge and just neck size. Use would need to use a separate decapping die.

You can also contact Lee Precision and they will make a custom sizing die for you for a not-too-bad price.

Looks like you're not the first to encounter this issue. See this page:

https://www.trackofthewolf.com/Categories/PartDetail.aspx/1171/1/CASE-43-SPANISH
 
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I would say find a straight-wall cartridge with the required diameter, buy the sizing die for that cartridge and just neck size. Use would need to use a separate decapping die.

You can also contact Lee Precision and they will make a custom sizing die for you for a not-too-bad price.

Looks like you're not the first to encounter this issue. See this page:

https://www.trackofthewolf.com/Categories/PartDetail.aspx/1171/1/CASE-43-SPANISH

Yeah, I have read that, but thanks for the link. I could probably neck size with a .45 Colt sizing die, but I still have a .454 throat and a .439 groove diameter. If I neck size to .439 or .440 it will just blow back out to .454 upon firing. What I am describing is essentially neck sizing, but just the very tip of the neck of the case and as little as possible. I think I can do that any number of ways.
 
Ahh I see. You can't even really do something special like paper patch the bullet to make up the gap difference, since the paper would ride along the barrel with the bullet. Maybe you could size the bullet and then build up the bullet O.D. with a ring of lube wax near the base to seat in the case?

Other than that, the simplest approach I can think of is just anneal the neck after every firing or maybe every other firing and just neck size.
 
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Ahh I see. You can't even really do something special like paper patch the bullet to make up the gap difference, since the paper would ride along the barrel with the bullet. Maybe you could size the bullet and then build up the bullet O.D. with a ring of lube wax near the base to seat in the case?

Other than that, the simplest approach I can think of is just anneal the neck after every firing or maybe every other firing and just neck size.

I think we are on the same page. This will be trial and error. Again the beauty of black powder is that one can play around like this. I would never attempt similar with smokeless. Too many variables. Thank you for the valuable input.
 
how do you seat a .454 DIA. lead bullet in the case. thumb press it in after shooting it? and can .452, 45,ACP heads be used?
 
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