Baikal shotguns are very well made and will stand the test of time.
I was interested to read the following:
Nice strong workhorse of a gun, some nice basic game scene details, wood is not at all bad looking either. I'd keep it for a back up but I need the cabinet space! Barrels measure 25&5/8" Choke is I think 1/2 and full, if I remember correctly although I don't have a choke gauge to confirm.
Baikal over and under barrels of that length are likely to be Skeet choked with true cylinder in the bottom barrel and bell muzzle in the top barrel.
Baikal bore diameters are normally 0.719" which is 0.010" tighter than most 12G bores, this makes people think a cylinder bore is in fact quarter choke when using a drop in choke gauge.
Bell muzzle on a Baikal is normally 0.729" at the muzzle which can make people think it is cylinder which it would be with a 0.729" bore diameter.
If you only have and use a drop in choke gauge you may think this is a load of rubbish but it is not.
If choke is important to you ask a gunsmith to measure the chokes with a bore gauge which compares the bore diameter to the choke diameter for you then you will be certain.
I have used a Baikal over and under for many years with a set of barrels just like these and find they will stop any target (live or clay) as long as I point them in the right direction.
Good luck with the sale of what looks to be a very nice shotgun.