It's very doubtful that after your rifle took a fall, that it's throat erosion. You've got something that's not in the same position as it use to be. Check your muzzle crown, your scope rail to reciever, or rings to reciever. I can not stress this enough, over tighting base screw, or any part of scope rings is just as bad as loose screws. Also, try a different scope, and ridiculous as it sounds I've seen high end scopes just get hit the wrong way. Check your bedding area, look for unusual wear areas, recheck your foreend for proper clearance. Check the trigger inlet to make sure something isn't binding, Essentially your gonna need to take the rifle all the way apart give it a very good look over. Oh yeah, definitely need to clean everything, and put some grease on your bolt lugs.