That is good to know. Thanks.I would recommend you skip the graphite. It doesn't play well with aluminum-
I could feel none when I had the mags apart for installing the bushings and polishing. Wouldn't hurt to look again, or to polish them at the point you indicated anyway.Have you checked the feed lips for burs 1/3 of the way from the rear of the feed lips?
The polymer casing? I pretty much ignored anything that did not bear against the follower itself. I thought the rounds bore only against the stainless upper.There are two points there that bear on the upper surface of the cartridge casing and I've deburred many that had casting flash back there.
I did polish the curved end of the feed ramp on each. Ran a piece of cotton clothesline coated with metal polish over it until it shines like a mirror.A small fine rat tail or chain saw file works best- go slow, draw gently and retest often, you're only deburring, *NOT* reshaping geometry.
Also, polishing the surfaces of the feed lips that the bolt glides on using a ragwheel and polishing compound doesn't hurt-
I guess it's time to open them all again and look for burrs. Sure wish these things were transparent.