I've ML about 10 years... I've had BP hard to get loosen and one that took a week soak in liquid wrench and had to purchase new BP removale tools because I ruined them.... This was just after I had a ML blow up in my face and thought the BP needed to be torque in with 100 lbs....

I' use to use Bore Butter... Had one misfire because of it.... I'm betting I was young and put way to much on.... I now use a fairly exspensive BP grease...... (it wasn't more then $18 but still) Just a little dabble on the front threads.... Screw it in hand tight...I can shoot 3-20 shots and it's no harder to remove...