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New M&P 40 marking my brass

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Neutered10mm

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Jan 5, 2012
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Eastern Panhandle, WV
I only have 100 rounds through it thus far, but upon chamber checking some dummy rounds for a new reload I'm working on, I noticed some scuff marks on the brass. If I slow cycle the slide, I can get a round to jam the action and can see that the case just below the mouth is being wedged against the feed ramp to chamber transition area. Below are some pictures to illustrate what's happening. What can I do to correct this? It's causing my lead load to crease the case because the lead bullet's lube channel is in this exact area.

FTF wedging:
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Feed ramp/chamber entrance brass buffing deposition:
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The result ... the "scuff" is very minor with nearly no indentation and only surface scuffing/burnishing upon a single clean chambering.
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However, after multiple cycling, I get this ... a rather deep ridge:
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BTW, this happens on all rounds fed through the chamber regardless of bullet. However, I'm reloading to save money and chose lead bullets to help save even more. I was wondering if I could buff out this section safely without worry of causing future problems.
 
Polish the sharp edge with a extra fine Cratex bullet tip in a Dremel tool.

Don't remove any metal just polish it.

As for wad-cutter feed problems?
That is pretty normal in a lot of guns.

In 1911's, mag feed lips can be tuned to feed wad cutters correctly.
Don't know about M&P mags.

rc
 
You are setting off a controlled explosion in your hand. Don't worry about scuff marks. They're ok, as long as it feeds when fired.

Or, to misquote a mentor, "They're GUNS, not Faberge eggs!"
 
LOL, I hear that and I'm not looking for pristine brass considering it's being subjected to 30K+ psi of pressure, but I do want it to feed reliably. The point of describing the scuff was to show how it's interfering with the cambering and it's not limited to just my reloads. Factory rounds are looking the same. However, at lunch today I took the dremel and polishing compound and brought the slide and entrance lip to a mirror polish ... feeds like butter now!
 
Is the Lead bullets sized to your barrel? If over size it may be a combination of thickness of brass and bullet size making it to large. With the barrel out do a plink test to make sure the round will drop in fully and fall out. If it does not fall out look to see where it's binding at. Rem brass has the thinnest wall. This is one reason some sort by head stamp.
 
Yep, everything drops in/out just fine. I ran into the head stamp issue when reloading and began separating rounds. This round of test loads are all Federal head stamps. Problem didn't occur during my first 100 factory rounds (Federal Champion) and is only occurring on manual slide racking. After polishing the ramp and lip to a chrome like finish, they feed just fine now as long as I don't ride the slide when manual racking.
 
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