Valmet/Tikka/Marrochi Finnclassic U/O double rifles and combination rifles have barrel rib spacers like this available.

In fact I have just bought several for my sets of barrels to give them a try. They were cheap so if they don't work, or affect anything, I'll just not use them. They have not arrived yet. Not sure how they are affixed yet, or whether a gunsmith is needed or not.

An example of Finnclassic's with the rib/spacer.

Probably doesn't help with a Baikal though, but it shows it can be done.