MD added the last point needed.
Barrels are female. Period. None are the same although many are "alike."
I would go ahead and open the channel to be dead certain everything floats all the time, .358 Norma is pretty sporty and there's a lot of force there that might have your metal AND wood flexing and vibrating in ways you never imagined. I've put dimes on top of the barrel near the muzzle and shot them off. Sometimes they orbit, sometimes they just fall off. So get clear first. You can do it "just right" without too much trouble, especially if the ACTION is properly placed.
If you like the "for sure" floating groups then follow that through with a nice thin liquid coat of epoxy to seal the barrel channel.
If you don't like those, go ahead and make a speed bump about where your experimental items were placed. Might work, might not. If it does, then do what John says and seal that wood after the speed bump is zeroed in, make it stable in weather.
