Any idea what might cause this?

[M&P Charlie]

The gun is an M&P 40C and has fired around 300-400 rounds. I am starting to reload now and have been picking my brass up. But I noticed something that it is doing to the cases. Any ideas?

 

[MSG Glenn]

Have those cases been reloaded before? Is it possible you're overloading powder in them making them +P or +P+? Are the projectiles being loaded with too much pressure causing bullet setback? Is this defect absent with factory loaded rounds? I don't know the answer to your problem nor am I a reloader. I'll be interested to find out what others say. I'd be afraid of one of them going kablam in the chamber.

 

[glen_farmer]

If that shell was the top cartridge in your magazine when you inserted it, that shell would have had a fair amount of pressure on it from the top as the slide passed over the top of it prior to picking it up and pushing it into the chamber.

I say this not because I have seen this, but I do know that the rib on the underside of the slide tends to get covered with brass as the gun cycles the cartridges through.

Then again. I could be completely wrong again.

 

[M&P Charlie]

This defect also appears on factory rounds as well. My nephew has a SW SD40 and fired these same reloads. His does not do this to the cases. What can I do to stop this?

Thanks.

 

[Iggy]

Looks like it's hitting the side of the ejection port or something.

 

[k31scout]

How is the ejection? Has it changed since it was new from off to the right or straight up? Does it do that every round? Could be the extractor is not maintaining consistent tension on the rim of the spent casing. I'd change the extractor which is a cheap part.

 

[M&P Charlie]

Pretty sure the ejection is normal but I haven't noticed it personally. Do you have a link to the extractor part? The gun is virtually brand new. Do you think Smith and Wesson would look at it?

Thanks.

 

[marlin.357]

Who made the cases?

 

[FloridaFlier]

Generally, S&W is a lot less interested in fixing your gun if you've been shooting reloads. Were you getting the case deformations with factory ammo? I'd shoot a couple boxes of factory ammo. If they give better empty cases, then it's something in your reloading procedure or equipment that's the problem. Good luck.

 

[3hounds]

Do you get the bulge from the feed ramp ?

If so, where is that bulge in relationship to the mark on the brass ?

What does it line up with on the gun ?

Is the case actually deformed (bent in ) or is that an illusion ?

If it's deformed it happens after he fires the round, so ammo would not be a factor.

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[3hounds]

Pretty sure the ejection is normal but I haven't noticed it personally. Do you have a link to the extractor part? The gun is virtually brand new. Do you think Smith and Wesson would look at it?

Thanks.

http://www.smith-wesson.com/wcsstore/SmWesson2/upload/other/PistolPartsList_Retail.pdf

M&P40C extractor 277630000 $1.65

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[M&P Charlie]

I said up above that my nephew is shooting the same reloads as me with his SD 40 and its not doing this to them. The case is bent in a little. No illusion. I've narrowed it down to the fact that its not the reloads due to the SD 40.

This happens with factory ammo as well.

 

[kudzu3]

Looks like it's hitting the side of the ejection port or something.

I believe this to be the problem also. Check the exterior area of the ejector for any signs of brass, shiney spots etc. When the brass is flipped out on ejection, it could be hitting something hard enough to cause the dented brass.

 

[M&P Charlie]

I dont really see any signs of brass. There could be a little near the ejection area but nothing significant enough to tell exactly where it's hitting.

 

[Jyezahn]

Kinda looks like the slide could be skimming the round when it strips off the round above it when chambering. Is it happening on all of them? Insert a loaded magazine and chamber the first round. Eject the mag and see if the top round has this mark, and check the bottom of the breech face for signs of brass shavings.

 

[kudzu3]

I wish I knew more about this, but is it possible that the shell is being flipped by the ejector in a way that it would be thrown back into the ejector itself with enough force to cause the dent? Does the dent match up with the exterior part of the ejector in any way? I'm only guessing about this, and don't own a M&P so am not speaking from experience but am curious. Good luck with it.

 

[cddanjr]

Are ALL the casings scraped like that?

From the photo it looks like the brass was on the ground and stepped on. the scratches are across the shell and taper away from the more solid end of the primer. Need more photos to determine any further.

CSI out.

Chuck

 

[Iggy]

Where is the brass landing? In front, back or off to the side like it should.

Extractor may be a bit tight and isn't turning loose quick enough and the case is dinging the side of the ejection port as it is thrown clear.

To the front or back in your face may tell you something.

 

[S&W Rover]

I can think of two possibilities:

#1. The round is hitting something on the way into the chamber -- maybe the top lip of the magazine is deformed. I don't think the round can actually hit the ejector -- I just hand fed a snap-cap into my M&P to check its precise path, and the side of the round in the front does not go near the injector -- the geometry and shape of the slide seem to prevent that. Solution to #1: Assuming you have two mags, does this happen with both of them, or just one? Chuck the bad mag.

#2. It might be hitting the ejection port on the way out -- my Sig SP2022 used to put a nice dent in every round, although further forward on the shell. That could be caused by a weak ejector. Solution to #2: Replace the ejector (per recommendations above).

If you have time, you could take a round and mark it with a magic marker/Sharpie™ (e.g., small dash marks at 3-6-9-and-12 o'clock clockwise around the outside of the shell) and then hand feed it in the chamber, with the number 12 at the top of the chamber, and then shoot it, and then see where the dent occurs. If there are dents/marks at all, it would argue for the dent occurring on extraction, not feeding. If the dents are at 3 o'clock, it would argue for the dent being caused by the ejection port.

 

[3hounds]

How can it be caused by feeding into the chamber ?

After a round is fired it of course forms to the chamber.

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