Argentino M1879 Rolling Block. Is it worth restoring?

[Claven2]

Another idea is to get some similarly sized fishing lures or other soft lead plug and a piece of steel flat bar. On a solid surface like a tile floor or a piece of sheet steel, roll the plug under the bar while putting pressure on it. Measure often - it will elongate and the diameter will shrink. When you get within 5 or 10 thou of the calliper measure groove depth, stop. You now have an appropriate slug.

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[killforfood]

I completed the chamber cast and a long winded, full of pictures description to follow…

The powdered graphite that I mentioned in a previous post was mixed with 4 or 5 parts sulfur and this sandwich bag is my (more than enough) results.



The next step was to plug the bore. Paper towels that you find in public restrooms are stiffer and work best.




I tapped the plug just past the rifling with a section of cleaning rod. The graphite is supposed to act like mold release but I still coated the chamber and action with a liberal dose of Johnson's Paste Wax.







The next project was to mold a pouring funnel out of car bondo and modeling clay. I would probably have skipped this step if I was using Cerrosafe but home brewed sulfur cast is nasty stuff to be spilling on a rifle.





I made sure that everything had a good coating of Johson's Paste Wax and started molding my clay.




Next I poured bondo into my hand formed mold and gave it a few minutes to cure. After pealing away the clay I had a funnel. It wasn’t pretty but at least I didn’t have to worry as much about spilling that nasty sulfur in the Wife’s kitchen… Well of course I did it in the kitchen, that’s where everybody heats things up.







Patrick, your suggestion of using a lead melting pot as a sort of double boiler got me to thinking… Hmmm, I could use that old fryer stashed in the basement. Its thermostat goes up to 400deg and that is plenty hot.



I heated the cooking oil just a few degrees above the melting point of sulfur and put my can of sulfur in and closed the lid.






While the sulfur was melting I pre-heated the barrel in the oven. I checked the barrels temp often using my hand. When it just got to the point that grasping it for a couple seconds was painful, I pulled it out of the heat.



The sulfur shrinks a lot during cooling. The funnel area allowed me to over fill the chamber to account for that.




I set the barrel outside to cool until it felt about room temperature. Then I broke up the bondo funnel with a pair of dikes and popped out the chamber cast. It actually slid out with just a few taps on a cleaning rod. Next time I will probably not go through the trouble of forming a funnel and just pour real careful.




Here’s a close up showing how well sulfur picks up all of the rifling details. I was very pleased with the results.




The next step was to take measurements.

Overall chamber length from breech face to the beginning of the rifling is 2.660”.

So Patrick, how did you know that this wouldn’t have a long throat when so many do?




Just ahead of the rim in the web area it was .526”




The shoulder diameter is .512”




The neck just in front of the shoulder is .464”




The end of the neck is .460”




And now the all important land and groove dimensions.
It’s a bit of a trick to measure 5 groove rifling but much easier than some lead me to believe.
I was able to measure the groove diameter by measuring along the axis of the bore and carefully twisting the casting until two of the grooves were touching the caliper jaws. The rifling twist rate was just fast enough to allow me to pick up two grooves. Casting about a half inch more of the rifling would have made this easier.
Groove diameter .442”




To measure the bore I twisted the calipers 90deg and measured perpendicular to the axis of the bore. This places one jaw on a land and the other on a groove. This gave me a groove depth of .006”. subtracting two groove depths gives me a bore diameter of .430”.



I’m hoping that all of this just means that I have a run of the mill .43 Spanish and not some cobbled up chamber. It just seems odd that this rusty rifle has a pristine chamber and I’ve been worried about this since the chamber looks too clean and shiny like somebody has been in there with a reamer.










Well, that's all I've got for now.

I assume Patrick that you will still want me to slug the bore to ascertain it's full length condition.

Claven2,
I bought some egg sinkers a week or so ago to try the method that you mentioned but they must have been very hard and probably too big of a diameter to begin with. I rolled them between two steel plates until my arms were tired but they were still to big to try and force down the bore. I will need to start with something smaller or softer.


Thanks for all of everybodys help and suggestions.
Thanks, Joel.

[Patrick Chadwick]

I assume Patrick that you will still want me to slug the bore to ascertain it's full length condition.

Yessir!