Not sure on break in, gun should run fine out of the box but I know some makers do recommend a break in period, one that come to mind is Les Baer, they recommend 500 rds I believe before a detailed cleaning. Of course LB's are tight as a frogs u-know-what out of the box. Oh yea and step away from the dremel, l think more feed ramps are messed up than improved by trying to fix something that isn't broke in the first place.
Believe NONE of what you hear; HALF of what you see and ALL you believe
Accuracy is king,penatration is queen but why not jack'em in the process if you can.