You can select which barrel fires first.
This is a double barrel, over/under shotgun.
Check the receiver, barrel(s), under the barrel(s), under butt place.
proof mark
A weapon that has one shotgun barrel and one rifle barrel either in an over/under or side by side configuration.
You may have to break the shotgun down in to the barrel section and the receiver section first.Look under the barrel section on the flat just ahead of the lug for the serial number.
Best left to a gunsmith.
Single barrel, under $100. Double-barrel up to $200 unless heavily ornamented.
No way to answer without knowing barrel length and gauge.
Under $200.
Nothing without you providing a detailed description of your shotgun,to include the model,serial number to age your shotgun and what type of barrel it has(single,double,over under etc.)also include if it is a plain barrel,solid matte rib,or vent rib barrel.
Try Numrich gun parts corp.or gun broker.com under shotgun parts.