Most of the time, the compensating screw in the action knuckle is very difficult to move. As a result, most people who attempt to move them, whether successfully or not, will leave some marks or damage to the screw slot. This is often done incorrectly when the real problem is wear in the bolt or the bolting surface in the rib extension.
One thing I should have mentioned is to make certain the gun is not cocked when you attempt to remove the barrels. The G Grade has cocking indicators. You can de-cock a Lefever without dry firing by opening the gun fully, then holding both triggers as you close it. Then remove the forend, and try removing the barrels, again making sure to push them back toward the breech as you open the gun. The cocking hook should remain down in its' recess in the frame. If it is coming up and cocking the gun as you attempt to remove the barrels, then the engagement of the cocking hook and the pin in the lump is incorrect.
Only the top of the cocking shook should be above the recess in the frame when you remove the barrels, as in this pic. The nose I spoke of is that near vertical area on the hook that faces the breech.
And here is a pic of the pin in the barrel lump that engages the slot in the cocking hook. If this pin is in that slot as you attempt to remove the barrels, you will not be able to remove them. I would not advise anyone who is not very familiar with this critical relationship to attempt doing any work themselves. A lot of so-called gunsmiths will mess this up.
