Sad MP 10mm 4" Range Report

[Bruno747]

Finally got a 4" 10mm MP this Friday. Took it to the range Saturday morning.

First of all, love how it shoots compared to my XDMs, like the trigger way more. What started happening I don't like so much. Never encountered this before so I don't even know where to start to address it other than calling Smith and Wesson. Maybe the hive mind here might have some answers.

I used Magtech 180gr 10mm which is reasonably hot and Hornady critical duty for this range session. Unfortunately about 25% of the time, the pistol will spit the last live round out the top and lock the slide back. It did with with both types of ammo, one mag seemed to do it more than the other but I didn't really try to test this too much because I was loosing live rounds down the range and didn't want to force everyone to stop shooting to retrieve them so I just started pulling the mag and reloading when the second to last round was chambered.

I will take it to the grasslands and put a bunch through it with 3-4 rounds in the mag each time and with the go pro recording in slow mo to see if I can catch what exactly is happening. These MP 10mm mags do seem to have very short feed lips on them compared to even my 45c. I have pretty much every other type of failure to feed, but this one is totally new to me. Tried to find some details online, but I can only find some references to some sig sauers doing it years ago.

I also need to do something about the grip on this thing. People must have gotten it into companies minds that they expect to have to use a pistol after having to dip their hands in gear lube. The stippling on this thing is way way over the top. Short of putting a rubber sleeve on it any un-stippling methods around that don't look terrible on the finished product? I haven't once grabbed my 45c and thought dang man this thing is just too slick I need to glue some sandpaper to it but anymore thats the entire MP line.

Aside from tossing the last round unfired out the top, and the meat grinder grip. I love this thing. I will be keeping an eye out for the 4.6" to permanently attach an optic to. I'll also be installing standard night sights on my 4". The "optic height" sights from the factory don't clear a fast fire 3 anyway.

[Kenk]

For the grip issue, you could always throw on Tallon grips. I have them on several of my pistols and really like them.

[sqlbullet]

My solution to overly agressive grip texture on a polymer gun is sandpaper.  Just rub some 220 grit on the grip until you knock enough edges off to be the right amount of grippy.

[Graybeard]

My solution to overly agressive grip texture on a polymer gun is sandpaper.  Just rub some 220 grit on the grip until you knock enough edges off to be the right amount of grippy.

That'll definitely work.

I bought an gen 1 palmswell from Midwest Gun Works for mine. It was under $6. The texture of the front and sides makes for a good grip on the gun without chewing into the web between my thumb and forefinger.

The last round ejection situation is unfortunate. I specifically ran my 4" M&P 10 with different power level and length rounds to test the reliability and didn't have a single bobble. Sorry to hear that there's a problem with yours. It makes me wonder if there was an issue with magazine production. Perhaps that explains why there are no spare mags available yet. Maybe some faulty ones got out into the world.

[38_Super]

In working up a load and testing my Kimber 1911 with the 10MM barrel I fit to it I had the issue of last round popping out of the magazine and the slide locking back with full power 180 grain loads.
After I upped the recoil spring to 22 Lbs it never happened again.  My guess is the slide was slamming back against the slide stop too hard from the lighter recoil spring and causing the last cartridge to move forward relative to the pistol and popping out of the magazine. Never happened again once I upped the recoil spring.

[bigboredad]

The last round popping out is your mag  pushing up the last round before the slide can catch it.   I had a 1911 45 that would due the same thing. To fix it I left the mags loaded for a couple weeks

[KS Gunman]

I had a Gen3 G23 that did this but only with one of the (10rd) mags it came with. Bought it during the Ass Ban, can you believe that - a "Blue Label" had to be sold with 10rd mags?!?! Those were strange days. Anyway-i would load 10rd, when I shot #9, the slide would lock back as #10 was ejected LIVE out like a piece of spent brass. Dumped the mag (we were past "sunset" anyway) and it never happened again. My guess - bad/weak lips.

On a side note, let us know how that M&P handles BB and UW, if you put any through it. Thanks.

[sparkyv]

I'd try this:

The last round popping out is your mag  pushing up the last round before the slide can catch it.   I had a 1911 45 that would due the same thing. To fix it I left the mags loaded for a couple weeks

[Bruno747]

As a followup to this...

Went to the grasslands and put a mess of rounds through it. First it was doing the same thing on both mags randomly would spit the last live round out of the top and lock the slide back. As best I could tell from slow motion on the go pro, its a combination of things.

1: The mag spring is weak. Thought this might be the issue given it takes less to put the 15th round into my MP than the first couple in my XDM.
2: The mag lips are wildly short compared to other 10mm firearms and even MP other calibers.

So watching the slow motion on the couple instances I managed to capture, the round was not pressed up against the lips before the slide battered back and started really racking the whole frame back. Inertia took effect and the round stays where it was when the frame starts coming back. By the time the spring in the mag catches up and starts pushing the round up against the lips, the round has cleared 50% or more of the lips. Once the spring has finally caught up and the slid is just starting to go forward the follower has shot the last round out of the mag and locked the slide back.

So as a temp test fix, I disassembled 1 mag and stretched the springs out as far as I dared. Put it back together and re-ran it. The mag with the stretched spring ran wonderfully, the original one still occasionally popped out the last round. Of course stretched springs only work so long before they go back to normal rate, so Ill be keeping an eye out for a wolf mag spring with significantly more force.

Also had one new failure, round nosed up and wedged between slide and barrel. In my limited 1911 10mm experience, this was also resolved by a stiffer mag spring.

All signs point to a couple new heavier springs to address most of the issues I experienced.

As a solid good side to the trip, once I got the red dot dialed, it had a super nice grouping. Soda Cans at 50 yards didn't stand a chance.

[Intercooler]

  I tried the XD-M and didn't like the grip on it. Our XD has always felt good in the hand! They should have built it on that IMO.

[Weldmeister]

I have been having the same "loaded round ejection" problem with my 4.6" gun, as well as it seems to like feeding the odd round into the barrel hood instead of the chamber.  I installed a Wolff guide rod and 24 pound spring and it helped, but didn't completely resolve the problem.  I installed a Wolff extra power magazine spring in one of the mags and that cut down the failure rate a little bit also...  Today I was out at the LGS and they had 10mm magazines, so I snagged one.   Once I got home I took it and the other stock magazine apart to compare them.   This is what I found:

The old spring is at the top, the one out of the new magazine on the bottom.   Neither one of these magazines had been disassembled before.  See the problem on the older mag spring follower?  So now I'm wondering if anyone else has checked this on their malfunctioning guns and found that the follower was installed backwards at the factory and if that could be a cause of all of our feeding problems with these guns.  I haven't had a chance to run out to the range and test the theory myself yet. 

[Kenk]

Sounds like someone?s first day on the job. Did you happen to to contact their Customer service about your find?

[Aegis]

For some reason the 4" seem to be more troublesome than the 4.6. I have 6 magazines for my 4.6 no issues at all. I have 750 rounds down range so far. My target load is 165 grain polymer RNFP with 4.7 grains of 231. I did replace the captive recoil spring with a Wolff guide rod and heavier spring.

[asteirman]

Funny, I had the same issue with some Pro Mags (low quality) for a Ruger PC40 many years ago.Purchased three mags, two worked great and third one was a problem child. Finally I realized they had assembled the follower backwards on the problem mag. Reversed it and problem solved. I just didn?t use that mag for a few years until it occurred to me . If you ever have this problem, then you will always think of this possibility. Nice job realizing this snafu.

Andy

[Weldmeister]

So yesterday I took the new magazine out to the range.  It did seem to perform better, but still not 100%.  I also installed a +10 Wolff .45ACP spring in one of the other magazines.  Didn't seem to make much difference.  Still getting these stupid failure to feed malfunctions, but hey, at least this time it only puked one loaded round out of the gun!  I don't understand this, as it runs my standard .40 S&W load fine, with no problems.  Which is stupid, because if I wanted another .40, I would have bought one.  Attached are pictures of the malfunctions I encountered while running some book safe, but honest 200gr lead flat points at a chronographed average of 1200fps.  Still looks like the slide is outrunning the magazine spring. Still using the 24lb. Wolff recoil spring.