A fellow shooter has a dovetailed Brno, that he loctited over 20yrs ago( dont know the actual number, but he said it was green and super strength grade)...
Now he cannot remove the rings or bases.
Hes tried heat application with allen key pressure to no avail,
Outside of cobalt drills applied to the grub screws,then an dental cutting wheel applied to the base lock bolt via the exhisting slit in the bases,.. is there any other minimal or zero destruction option available?
Heres an example of the mounts;

There is nothing wrong with drilling out the headless set screws.

Before he tries drilling, he might touch a pencil tip soldering iron to one of the set screws to see if the Loctite will turn loose.

If there are cross screws in the bases as in the photo they can be drilled from the head end just deep enough to cut the heads off. If he wants to try the soldering iron on them he should touch the other end of the screws.

To break green locktite you need to get the screw up to 450 Degrees F Minimum
I'd order a carbide drill and drill out that set screw