I read your post the other day and forgot to respond. First off (Per EAA Corp & Remington Arms) Baikal does not make extra barrels available for sale. Now why... The barrel on the MP153/SPR453 is individually fitted to the receiver at the Baikal factory. Now I have tried to swap barrels with others that have this shotgun. 3-wouldn't fit and one actually did. Two could probably be altered that fit too tightly. The other barrel was way too loosely fitting in my MP153 receiver. Bottom line is barrels on these shotguns generally can not be swapped for one gun to another (Plug and Play) like most semi autos or pump shotguns. And extra spare barrels are not available anywhere that I know of. If something happens to your barrel EAA service will fit a replacement barrel under warranty or non warranty repair. But one can not purchase an extra barrel for their gun.
My information here comes straight from the EAA Customer Baikal service center a few years back. I would show you a copy of the email but I deleted it about a year ago. EAA/USSG also handles all warranty service, repair and replacement parts for Remington Arms regarding all Baikal built models.
THANK you very much, thats pretty disappointing, I would love a gun thats more versatile than this, I should have done some homework