Eish Sahib - that is a long and interesting one - Mods this doeasn't fit under Roe bucks so move it to more appropriate place if needed.

Anyway - I have sold that double years ago - it was converted from 7x57R/16 combo. 16 ga barrel /lower one) was blown up due to soil plug - I was solving a close fight between a terrier and a badger (holding a dog with one hand and unintentionaly leant on a rifle.

Upper barrel original CZ (Poldi special steel) in 7x57R - additional (lower barrel) Ferlach (Bohler rasant) in 7,62 Russ, stock was right handed with fancy cheek but utterly unpleasant for lefty, so it (the cheek) was later grinded off, there was a Schmidt & Bender 4x36 mounted with Suhler einhack mount. The rifle was never meant for shots over 150 m - mainly used for tracking and driven hunts, so at the end the first trigger (upper barrel) was cut off and it became ST (first pull lower barrel, second pull upper one).

Why 7,62 Russ - After Balkan war moved down to the south back in nineties, there were zillions ammo left behind and I found it would be a pure waste if I don't find any use of them. Amongst others 7,62x54R came to front. Tho right from the beginning problems arise. Bullets were military ball type and as such not quite felicitous for hunting use. So I have drilled the bullets made them HP - also glued pellets on the tips on some. They worked like a charm on all hoofed animals encountered here in EU. They made good exits on all game- with app. 1 inch dia.

Accuracy - If memory serves me well it was app 2 inch at 100 m (7,62 Russ with 150 and 170 gr and 7x57R combined) - tho nowadays Norma and Lapua offer good factory ammo.

Ammo used - from left to right:

1. PPU (Prvi partizan) - military - brass 170 gr copper bullet FMJ - drilled with glued pellet insert - HP
2. Russian military steel copper plated case 150 gr steel coppered FMJ bullet drilled - HP
3. Russian military 150 gr tracer bullet
4. for comparison 7x57R

Next one was tougher. Since this caliber was made for Russian machine guns, there were those nasty thick corrosive primers. Due to the thickness of the primers there was occasional hang fire because the firing pin on a double just couldn't break it. So I planed the primers on the lathe a bit and it worked without any problems since (still had to clean the barrel for a week or so after every shot tho.
Primers - Left original one, right one »worked on«

However there was more to it (as usual) - since primers were planed they were further away from a firing pin's reach so the pin had to be custom made (longer) so it jutted out a bit - meaning that when using normal ammo the pin was slightly pushing against primer (there were visible scratches on the normal primers) + since primers were worked out with certain accuracy there were unavoidable differences and in two occasions the primers were thinned bit too much so the pin pierced them through (when shot of course) and on one of those occasions (when the rifle was opened) the pin broke.