Polish the chamber....is that what they are calling it these days?
Find the largest Dremel attachment you can and grind away at your chamber as long as you can. If you see lots of sparks you are doing it right.
Oh you wanted SERIOUS answers. . . .
How exactly would you polish the chamber? I've been searching old threads about M&P's having FTE, and a lot of guys have solved the problem by polishing the chamber.
How do you do that? Any pics or videos?
So your saying to lube it up, then rub it hard? Sorry, had to do it.if you want to polish your feed ramp with a dremel, don't use a grinding wheel attachment. get a felt tip wheel and appropriate polishing compound for the metal you are working with (guessing stainless for your m&p's barrel??). various grit compounds are available. the higher the grit, the smoother your ramp, assuming you know how to work it in.
If you don't know 110% what you're doing...don't do it yourself. At least not without someone who DOES know, coaching over your shoulder.
Polishing is taking off metal... metal that you can not put back if you screw up.
YMMV