Rechambering shotgun - Good idea?

G

Gungnir

New member
I need advice before I have work done to my shotguns.

I have a couple of old SxS shotguns, both czech BRNO Special Poldi guns from the 60s, which I use for duck and goose hunting. The guns themselves work flawlessly with the 12/70mm ammo they were designed to shoot, even with steel shot, but lately I have been wanting the option to load 12/76mm magnum shells to extend my effective range. A local gunsmith has offered to rechamber the guns, but I am having second thoughts. Will it be safe to just modify 50+ year old guns to load higher pressure ammo than what they were initially designed for? Will it affect their patterning? And will the more powerful 12/76mm shells allow me to engage birds at significantly greater distances?

Thanks :-)
 
Welcome!

Is this gunsmith someone who regularly works on old SxS guns like these? If not, I'd get a second opinion. It MAY be OK, it may not. The amount of steel where is wants to remove it is important. What is the proof of the current guns versus the pressure you'll be wanting to use. In most Euro countries, when something like this is done, the gun needs to be reproofed (and stamped accordingly)
 
The maximum SAAMI pressure for both length shells you list (2-3/4" & 3") is the same. The 3-1/2" / 89mm shells are listed higher. Since most SxSs don't have a quick taper on the outside of the barrels after the chamber and are originally designed with a safety factor, you will probably be okay. If I were lengthening the chamber or the forcing cones I would want a barrel thickness profile in the affected area and check the theoretical strength. A proofing shot(s) is always good insurance, but not much help before the act.
If you are shooting steel with no issues through fixed chokes on a SxS I wish you continued good luck. If my memory serves those guns had fairly thick barrels.
 
Yeah, the steel through fixed chokes part worried me as well when I got the guns in the first place, so I had a smith open the bores on one of them (72 cm/~28" barrels) to 1/4-1/8, and shorten the barrels of the other one to 55 cm/~22" cylinder bore. Overall the guns are performing well with steel shot, though the short one only patterns well with some ammo.

I have decided to go ahead and have the chambers modified, and to have the smith reproof the guns afterwards.

Thank you for your time :-)
 
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These days with all the choices of ammo, you can probably get what you want with a change in ammo, rather than risking modifying the barrels.
 
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