That is the French or Military brass-barreled blunderbuss as sold by many outfits like Veteran Arms and Military Heritage, amongst others. They sell for $600 to $700 or more, depending if in stock, as I'm sure the higher price reflects those that are available as of late.
On YouTube there is a channel called 'InRangeTV' where they shoot one of these a lot and have videos on different loads and wads. Or send an email to either VA or MH and ask for their loading info, as they provide a load sheet with each piece sold. I'd say 60-grains 2Fg or less would be perfect for using these for what they are.
Breeching - If in doubt - proof it, double load, double ball or shot, using safe proofing practices, etc. That said, I've proofed 3 Indian arms so far and even had Bobby Hoyt check out another one and all were sound and integral - no issues. All still shooting to this day, even though I only kept the best one ... the 2-1/2" bore hand mortar ... for myself!
FYI, the MH site has details on the steel it is made from and an overview of the production process. I also have 2 test reports on Indian-made barrels of the DOM process, Drawn Over Mandrel. One survived proof loads up to 400-grains of powder (CAUTION - Proof load testing only!) and 2 patched roundballs at which the test was stopped so as to just stop wasting powder (see attached test report). That is one test that I shall not repeat, haha!
The other test is by the highly respected testing laboratory of H.P. White. That was a barrel used by a reenactor with blank charges, of which it is believed that a few may have been stuffed down the barrel before it finally went off, as the cause was an obstruction a good foot or more forward of the breech. Their analysis found no microscopic or grain structure/material defects with the barrel or the barrel steel.
My summary - Indian-made arms may not be for everybody, I certainly understand that - but they can be shot ...
