Recently acquired a double rifle.
Proof marks are Austria, circa 1890's to early 1900's
No nitro marks, so black powder.


Bore is 12.8 mm, (0.504")
From the chamber casting, its a 12.7 x 60 RD


Its a continental version of a 500 BPE in a 2 3/8 length, rather than 2", 2 1/4, or any of the other lengths up to 3 1/4.
Case length falls between the 50/70 and 50/90, and closer to the 50/90.

This seems to be a bit of an obscure round, and I have only located 1 image of it and no technical information.

I have figured out a few options for parent brass. None are trivial
Even the 500 nito will require a reduction in head diameter and a slight modification to the body taper.


Does anyone out there shoot this round or know anything about it.

Any knowledge on the original specks for the factory rounds - powder charge or bullet weight.

I suspect I need to start somewhere in the ball park of the factory loads or regulation of the round will be an issue, and I am trying to save a few iterations.

I have worked with obsolete shells in the past, but never in a double and never with one this hard to find information on.

Any assistance or advice is appreciated.

I for one would like to see images but from what you describe have a gander here:


https://naboje.org/en/node/2597

Of course it was developed by Roth in the 1890s & it is the 500 BPE 3" shortened to 60mm & held a 26,6 gramme bullet.

Cheers,

Raimey
rse

Also, I am in the throes of loading a >>Biks<</Cape in the 10mmX60R variant and it prefers a compacted case of black powder substitute(for now), possibly dropped down a tube, and a bullet a with a bit larger diameter than 10,0mm. I am having trouble with cases sticking......

Cheers,

Raimey
rse

ahall,
For donor cases, I suggest 59-90 Sharps, from Starline. They would need to be trimmed to length and the rim may need adjustments to diameter or thickness or both. The head diameter should be OK as is, but if a little large, that can be handled.
Mike

Raimey,

Thank you for the link.
That gave me some dimensions to work with in addition to the bullet weight.
I should be able to work out the projectile from that.

The gun will regulate for a specific charge, so I should be able to find it now that we have a bullet weight and geometry

That leaves me with powder charge ----- Unless someone knows the charge of BP or a velocity, I am just going to have to start light and work up.
The case volume will be a bit under the 50/90, and 90 gr was for an old balloon head case. Any thoughts on how to decide when we have gone far enough if the gun does not find something it likes with a 410 gr bullet.


Brass - I turned a case head from a hunk of brass - rim thickness is 0.050" - So 50/90 will require some rim thinning and length trimming. Both well within the capabilities of my tool kit.

32 Ga magtech is another option. The head is weaker, but its probably closer to the original case volume. I need to check the rim thickness and base diameter. It might be too big at the base.

500 nitro - correct rim thickness, in theory, but head diameter is a fuzz to large according to my references.


Thank you for the assistance

Ah, for the powder charge, just fill the case w/ black powder and set a bullet atop it. That seems to be the correct manner in which it was loaded. You could fill the case & see what it measures. But I would fill the case & check the velocity. I suspect it was around 1500 ft/s. But where the bullets land up on the target @ a distance of 100 paces just may be the test?

Cheers,

Raimey
rse

And the old timers had pretty good powder so start with some Swiss. With a double you're fighting two devils: the crossing of the barrels and the matching to the sights. Get lots of powder and get ready for a lot of testing.