Argentino M1879 Rolling Block. Is it worth restoring?

[Patrick Chadwick]

will my .45cal lead bullets work ok instead of round ball? Obviously the round ball would be easier to drive through but it comes down to being what i have on hand.

DON'T TRY IT

I have not yet succeeded in finding anything resembling standards for the .43 Spanish chambering. Any drawings that may exist could only be taken as guidelines.
The bore should be somewhere in the region 0.410" to 0.430" mm, and although the grooves are much deeper than for modern calibers, you have to recognize that this is nearer to a 44 than a 45. You would not try to drive a 45 bullet through a 44 barrel.

The groove diameter will be somewhere around 0.440" - 0.450". Modern handgun bullets are far too hard to be driven through a bore by hand, unless you use the kind of force that is going to be hazardous for your barrel. It will not be feasible to get the degree of upset/obturation/bump-up - call it what you will - that is required to fill those deep grooves.

YOU MUST USE A SOFT LEAD BALL OR BULLET if you want to get the groove depth.

A 429-430 lead bullet might go, but that would only give you the bore diameter, not the groove diameter. OK - that would be better than zero information, which is our present state of knowledge! But if a 429 bullet will not go down with the brass rod method, give it up and knock the bullet out again.

Information

Warning: This is a relatively older thread This discussion is older than 360 days. Some information contained in it may no longer be current.

[jmoore]

DON'T TRY IT

I have not yet succeeded in finding anything resembling standards for the .43 Spanish chambering. Any drawings that may exist could only be taken as guidelines.
The bore should be somewhere in the region 0.410" to 0.430" mm, and although the grooves are much deeper than for modern calibers, you have to recognize that this is nearer to a 44 than a 45. You would not try to drive a 45 bullet through a 44 barrel.

The groove diameter will be somewhere around 0.440" - 0.450". Modern handgun bullets are far too hard to be driven through a bore by hand, unless you use the kind of force that is going to be hazardous for your barrel. It will not be feasible to get the degree of upset/obturation/bump-up - call it what you will - that is required to fill those deep grooves.

YOU MUST USE A SOFT LEAD BALL OR BULLET if you want to get the groove depth.

A 429-430 lead bullet might go, but that would only give you the bore diameter, not the groove diameter. OK - that would be better than zero information, which is our present state of knowledge! But if a 429 bullet will not go down with the brass rod method, give it up and knock the bullet out again.

I think the first step is just to roughly measure the groove dia. with a pair of calipers at the muzzle if it's not altogether bell mouthed.

Contrary to Patrick Chadwick, I'm thinking those above bullets may just work.

I believe those Speer bullets are swaged, not cast and are dead soft. So if your bore (grooves) runs 0.447"+ then I think it'll work fine. Just start it w/ a large hunk of nylon or delrin, IF they are the swaged type. I've done similar plenty of times w/ no ill results.

One COULD also reduce the diameter of the rear of a test bullet to reduce the bearing surface. Stupidly, if you have a lathe available w/ collets, just squeeze the back end a bit. Almost no force would be required!

[Patrick Chadwick]

the muzzle if it's not altogether bell mouthed.

I think we would all find it useful to have a pic of the muzzle end of the rifling now.
You previously posted pics of the throat end. They came out very well, because the chamber was in shade. so you could focus on the throat, which is lit up better than the surroundings.

However, at the muzzle end it is the other way around - the bright surroundings of the crown and background make it impossible to get a good photo of the vital last half-inch of the rifling.

Use a piece of plastic pipe, cardboard tube etc to make a hood for the muzzle, and then you can focus a camera on the rifling, which will then be brighter than its surroundings.

[killforfood]

I think the first step is just to roughly measure the groove dia. with a pair of calipers at the muzzle if it's not altogether bell mouthed.

Contrary to Patrick Chadwick, I'm thinking those above bullets may just work.

I believe those Speer bullets are swaged, not cast and are dead soft. So if your bore (grooves) runs 0.447"+ then I think it'll work fine. Just start it w/ a large hunk of nylon or delrin, IF they are the swaged type. I've done similar plenty of times w/ no ill results.

One COULD also reduce the diameter of the rear of a test bullet to reduce the bearing surface. Stupidly, if you have a lathe available w/ collets, just squeeze the back end a bit. Almost no force would be required!

I have some 44cal lead bullets that would work except that they are hard cast for my 44mag.