New to Me Antique H. Burgsmuller Double Rifle Unsure of Chambering

[EBaker]

I recently got this H. Burgsmuller double rifle. It also came with a set of 2.5" 12 gauge barrels. The seller didn't know what it was chambered in, just that it was a 43 caliber. It has Belgian proof marks that I'm told indicate a proof year of 1883. I cast the chambers with wax and found them to be extremely close to 444 marlin. In fact the shorter hornady 444 marlin brass doesn't even need to be trimmed to work. I loaded some 444 bras with black powder and soft lead bullets and it shot well. I'm wondering if anyone may have any ideas as to what the original chambering would have been. I've looked around quite a bit and I may just not be looking in the right places.

 

[318AE]

It may be a 11mm Mauser. I’m glad you cast it.

 

[EBaker]

It may be a 11mm Mauser. I’m glad you cast it.

That was my first thought too. I even ordered some before the gun came in to try. The problem is that it's a straight wall and the mauser is bottlenecked. The mauser also has a .446" diameter bullet.

 

[EBaker]

Update: I got a suggestion that it had been rechambered 10.75x60r Grundig in the early 1900s on Facebook and that definitely makes the most sense. It is nearly identical to the 444 marlin.

 

[Shootist43]

EBaker, it sounds like you are on the right track. I'm sure one of our "vintage Double Rifle Experts" will chime in shortly with some additional suggestions or information.