I have an older Baikal SxS that is gorgeous with decent engraving, 'cocked' indicator pins, that beautiful finish that comes from case-hardening, I believe, and a side lock in addition to the bottom locks. My cousin bought a more recently made version that is simpler, with regular blued steel receiver, minimal engraving, no side lock, and no indicator pins but still very tight.
On the other hand, someone I used to hunt with bought an O/U a few years back that took two hands and considerable force to break open. The fit was so tight it was impractical. Not sure how many thousands of rounds it would take to loosen it up. I think he eventually took it to a gunsmith to have it loosened.
Your mileage will definitely vary. I'd highly recommend trying the specific gun you're interested in buying in person prior to deciding on it.