Scope leveling , easy .
Get a two or four foot level , whatever size fits your backer board .
Mark a level line across backer were you figure top of target will be .
Hang target with top matching the line .
CTK rifle level is a Jim dandy device that can easily be used from weapon to weapon .
Set rifle in bags , level rifle with rifle level while looking through scope .
Level scope cross hairs with top of target making sure rifle is still level .
Start snugging ring screws in crisscross procedure .
Check level again before final torque.

Muzzle flash as mentioned and fugging idiots that open fire on a deer you just shot at .
Dumb azzes that try finishing off a deer by repeated body shots at point blank range .
Numb nuts that keep cranking rds through their rifle wondering WTH is wrong with it .