What is causing this? (M&amp;P40)

**amd5007** · 05-09-12, 22:37

It looks like they just polished the ramp and called it good enough. I would contact S&W.

Does it do this with brass/steel/aluminum casings? Hollow point and jacketed rounds? Does it occur during rapid strings or slow fire?

If it did this out of the box then S&W needs to know about this and really fix it.

**Biggy** · 05-09-12, 22:41

I would make sure the mags springs are good and have the latest #9 stamped follower. I would make sure there is no burr or sharp edge on the extractor, so the cartridge slides under it without binding. The extractor spring is most likely okay as long as it is not out of spec and to strong. Make sure there is no burr anywhere on the breech face or feed ramp. Polish the feed ramp . Replace the recoil spring assembly if it is old and weak.You might also try using mags from an M&P that is known to be reliable. If it were my pistol I would keep sending it back until they (S&W) get it right.

**ZoomByU** · 05-09-12, 23:47

Originally Posted by amd5007

It looks like they just polished the ramp and called it good enough. I would contact S&W.

Does it do this with brass/steel/aluminum casings? Hollow point and jacketed rounds? Does it occur during rapid strings or slow fire?

If it did this out of the box then S&W needs to know about this and really fix it.

Does it with brass and aluminum fmj. Was goin to try jhp next time. Happens fast and slow fire.

**amd5007** · 05-10-12, 07:17

Originally Posted by ZoomByU

Does it with brass and aluminum fmj. Was goin to try jhp next time. Happens fast and slow fire.

Yeah S&W needs to take it back.

**RogerinTPA** · 05-10-12, 07:28

Interesting. Have you tried cleaning and lubing it? I say that because when I first got my M&P40 years ago, I bought it at a gun range and shot it as soon as I bought it and had similar issues. As soon as I added lube, the problem went away.

**ZoomByU** · 05-10-12, 08:10

Originally Posted by RogerinTPA

Interesting. Have you tried cleaning and lubing it? I say that because when I first got my M&P40 years ago, I bought it at a gun range and shot it as soon as I bought it and had similar issues. As soon as I added lube, the problem went away.

It was dirty this time but was lubed up.

**Aray** · 05-10-12, 08:47

Send it back again, and be clear that this is the second time with the same issue. I would include the pictures and a detailed description like the one you gave above.

I have had good response from S&W in the past.

**NCMedic** · 05-10-12, 09:17

Do you have your magazines marked somehow? Does it happen with one magazine or all of them?
I'd probably still send it back to S&W with the photos and a detailed description of the problem, wouldn't hurt to tell them that it was supposed to be a LEO firearm either.

Sent from this... Using that...

**goteron** · 05-10-12, 11:12

It looks like an extractor issue. I would pull the extractor out, check the channel, spring, etcl. Put a slight radius on the leading edge of the extractor, replce the spring and give it a go.

I have Apex FRE's in all of my M&P's and had to give the extractor a good radius / polish to get them working really well (As Apex suggests)