Lubricate and clean ...the threads inside the barrel ( with Break Free CLP ) ...use a toothbrush or whatever to get in there....and same thing on the choke tube threads...
get them both real clean....and then use Break free again ( a lot of it ) ...to lube the threads inside the barrel ...and the choke tube threads....
My concept is ....they should go in and out of the gun smoothly ...with no hitches...by just finger pressure / put a finger inside the tube and run it into the gun. If it grabs at all going in or out ....repeat the cleaning ....and do it again and again until they go in and out.
and clean the darn things inside and out ....after every range trip.
Briley Mfg has chokes for the Baikals ...they use the TruChoke system last I knew...and I think Briley sells them for around $ 20 - $25.
If you can't get those threads to work cleanly ....you might need to "chase" the threads....but be really careful / because if you screw up those threads ..it can get expensive.
And if you have a choke tube wrench ...put it away / and only use those things in emergencies...when you can't get a choke out of the gun with finger pressure....but choke tube wrenches screw up a lot of guns cause guys crossthread them and then crank em in there..without realizing what they're doing.