Double Feeds

[RichardInFlorida]

What causes double feeds in semi-auto handguns?

I recently picked up a S&W M&P (full-sized/9mm). The first 100 rounds of Federal 115gr +P+ ran fine. The next 60 rounds of Speer 147gr Gold Dot was also 100%.

I tried 20 rounds of reloaded 9mm (local source) and got two double feeds. I then ran through 100 rounds of Winchester White Box and got two double feeds.

Just to clarify, I am defining a double feed in this manner: When I depress the trigger, the round in the chamber fires, but the brass case is not extracted. A fresh round attempts to be loaded into the chamber, but the nose of the new bullet is jammed into the old case. The slide is out of battery. The clear the malfunction, I have to strip the magazine from the weapon and then work the slide to clear the spent case.

Ok, any ideas on what is causing the problem? Bad ammo? Bent mags? Some type of extractor problem?

Thanks for all suggestions,

Richard

 

[armed85]

What you describe is a failure to extract. A double feed is when one live cartridge is chambered and then another live cartridge is jammed behind the first.

Your malf is similar, but the spent brass should of been extracted, thus failure to extract.

The reloaded ammo sounds like it's undercharged. That is to say that it doesn't have enough recoil to operate the slide properly.

The Winchester ammo should of fed properly. Was it two boxes or one of those 100 round value packs? You could of got a bad batch.

Try 50 to 100 rounds your ammo with the other magazine. Then go back to the first magazine. It might be a bad magazine.

If you continue to have malfs with both magazines, then it's back to Smith & Wesson for warranty repair unfortunately.

 

[The Lone Haranguer]

This sounds like an extractor problem. As an example, my Sigarms GSR (the first one) started having this problem, and I looked down into the ejection port with the slide locked back and found the claw of the extractor broken off. Yours may not be this extreme, but it is possible for fouling to build up between the extractor claw and breechface, or the spring inside the slide and behind the extractor may be weak or broken, either of which will cause the claw to slip off the case or not push deeply enough into the case groove.

 

[pdowg881]

You've probably done this, but always give it a good cleaning and try different amoo first.