10mm FTF (yet another one) troubleshooting

[andyshoots]

Unless I'm totally missing something, you don't describe the failure in detail. Is this a failure to eject the spent casing after firing, or a failure of the slide to close completely into battery? Double feed? Or something else perhaps.

If it's not ejecting the casings, you may be getting a clue from the Underwood ammo, in that the Underwood ammunition is loaded heavily enough to open the slide fully, while the other more "conventional" practice ammo you're using is not.

Failure to feed sorry, specifically failure to chamber, half the round makes it in before the slide crunches down on the case and even dents it a bit.

 

[andyshoots]

Sounds to me like the barrel feed ramp and hood have tool marks left from manufacturing. Some light polishing by hand with fine sandpaper might fix it right up. 1000grit and then 2000 grit works well with the thumb.

I have fixed lots of guns that didn't feed well this way.

Interesting ok, I have some 2000 grit laying around. I've been holding off doing anything to it myself in case I send it to S&W I don't want them to say that it was ME who caused the problem...

Still trying to get to the range to shoot the 100 Underwoods I just bought to see if they really do function 100%.

 

[rosewood]

I don't think they will even notice you doing light polishing on the feed ramp if you stay there with 2000 grit. Just don't knock off any of the bead blast finish on the outside of the barrel. The ramp should already be polished somewhat anyway.

Rosewood

 

[Hair Trigger]

No personal experience with the M&P, but failures to fully chamber that look like that can be caused by too much extractor tension, sharp or rough edge on the bottom edge of the extractor, a magazine that is not keeping the rounds at the correct angle for proper feeding or magazine feed lips that do not release the case soon enough for reliable feeding.

Try a simple plunk test. Drop a sample of cartridges from each type of ammo you shoot into the chamber. If some don't go in all the way, your chamber is undersized, and S&W owes you a new barrel. Admittedly, this is a remote possibility, but it's an easy check to make.

You might also try polishing the feed ramp. Don't overdo it with a Dremel, just use some car polish, Q-tips, and a cleaning patch.

Like stansdds, I have not specific experience with the M&P, but I did have a Commander-size 1911 that did the same thing, a EMP4 in 9mm. Plunk-tested just fine, but lots of issues like you show, round halfway in, or slide just out of battery. I sent mine back to Springfield. They reamed the chamber, polished it and the feed ramp, tuned the extractor and pinned the ejector (that was a not uncommon EMP issue). When I got it back, it ran perfectly. I think tuning the extractor meant the may have polished the bottom edge a bit, to allow better feeding of the case rim under it as the case moved into the chamber. Reaming the chamber opens it up just a tiny bit, they didn't specify how much, but I suspect they ran the standard reamer through it again and the polish took care of any reamer marks that might have snagged the case mouth as it fed. You can easily polish the chamber and feed ramp yourself with a Dremel hand tool and a bullet-nose polishing bit (see picture). The one I have fits perfectly into a 9mm chamber, and just barely loosely in a 10mm chamber (that's a 10mm barrel and cartridge in the picture). I've done the feed ramp and chamber on my .40 S&W 1911 this way. Used a little Flitz and it does the trick; it's a very mild polishing compound, so you can work it pretty hard without taking too much off. Do a little bit, try the gun for function, try a bit more if it still FTF's, until it feeds reliably. Or, send it back to S&W and wait, since it is under warranty.

 

[AlHunt]

Interesting ok, I have some 2000 grit laying around. I've been holding off doing anything to it myself in case I send it to S&W I don't want them to say that it was ME who caused the problem...

Still trying to get to the range to shoot the 100 Underwoods I just bought to see if they really do function 100%.

Wow, you're going to shoot over a hundred bucks worth of ammo just to see if a 5 or 6 hundred dollar gun works?

I'd save my money and lose that dog in a heartbeat.

 

[andyshoots]

I don't think they will even notice you doing light polishing on the feed ramp if you stay there with 2000 grit. Just don't knock off any of the bead blast finish on the outside of the barrel. The ramp should already be polished somewhat anyway.

Rosewood

Thanks Rosewood for the suggestion, I watched some videos, and used I think it was 1000 grit (been a few weeks now) and polished up the chamber, it went from not wanting to manual cycle to manually cycling (still not as smooth as my s&w 9mm but it manually cycles fine just have to let the slide drop fast, no sluggish releases).

Finally made it to the range today, shot 137 rounds of mixed 10mm, 0 problems! Normally I would have had ~5-10 failure to feeds.

Woohoo!

 

[rosewood]

Thanks Rosewood for the suggestion, I watched some videos, and used I think it was 1000 grit (been a few weeks now) and polished up the chamber, it went from not wanting to manual cycle to manually cycling (still not as smooth as my s&w 9mm but it manually cycles fine just have to let the slide drop fast, no sluggish releases).

Finally made it to the range today, shot 137 rounds of mixed 10mm, 0 problems! Normally I would have had ~5-10 failure to feeds.

Woohoo!

Glad I could help!

It will likely slicken up even more over time just from friction with the ammo. That is the "breaking in period" you hear so many discuss. If things are polished like they are supposed to be, there is no "breaking in".

Rosewood