Update 5:

It chokes!

Wen out to the indoor range after the outdoor session when it ran flawless. It started having a different sort of jam. Rounds were flat horizontal in the magazine with the nose of the bullet jammed up against the feed ramp. Seemingly random and not the usual 2nd to last round. 5 jambs in 250 rounds fired with Aguila, Blazer Brass and Fiocchi.

Replaced the Wolff extra power magazine springs with units from Springer Precision. Springer claims that these are a fix. They are significantly longer than the Wolff springs. Long to the point they're a PITA to get into the magazine body and get the baseplate back on.

Range session tonight, 150 rounds fired Winchester, Blazer brass and S&B. One failure to feed on the last round in the magazine with S&B. Maybe it was an ammo issue, but given my history with this gun I'm still not confident with it.

Update 4:

IT WORKS!

Last time out before today, loaded 5 rounds in the magazine, did its usual hiccup on the second to last round in the mag and jammed the nose of the bullet up into the barrel hood. I cleared it and threw it back in the range bag in disgust.

Today went out with a co-worker who has own YouTube Channel, Chuke's Outdoor Adventures. He has a 4.6" M&P 10mm that has been problem free so we set out to make a video comparing the two. Three different shooters put 400 rounds of 7 different types of ammo through the gun today and not a single hiccup. I'll post a link once he finishes editing and posts the video.

Nothing changed today since I last shot it. To date; back to Smith & Wesson once to have the barrel replaced, replaced the magazine springs with Wolff Extra Power springs from the M&P .45, Galloway Precision 22LB. recoil spring assembly, and polishing of the feed ramp and chamber by me.

It works! I'm happy, I've really wanted to like this gun, 15 rounds of 10mm in a Commander sized package but felt I just couldn't trust it. We shot everything from .40 S&W power level stuff to Underwood 200gr. hard cast, even mixing 3 different types of ammo in the same mag and it performed.

Also shot Chuke's Sig XTen, Springfield XDM 10mm and Gen 5 Glock G20. I was impressed with the XTen but was almost afraid to shoot, afraid that I would have buyer's remorse over my Smith & Wesson. In the end not having buyer's remorse. While similar in size, the Smith does feel lighter and more svelte for a carry gun of the XTen.

So in short if you're considering a 4" M&P 10mm, expect to swap recoil springs, mag springs, do some home gunsmithing and a few hundred round break in period.

Update 3:

Installed 22lb. recoil spring assembly from Galloway. No difference at all. Still consistently jambs the second to last round from the magazine no matter what the ammo.

Wondering what to do at this point. I'm going to try and run the standard magazine spring with the 22lb. recoil spring and see if that does anything. I'm also going to look at it tomorrow under better lighting and see if polishing the feed ramp or the underside of the barrel hood might do anything.

Update 2:

Extra power magazine springs had no effect whatsoever, it still consistently jambs the second to last round in the magazine no matter the ammo or how many rounds are loaded in the magazine. 22lb. recoil spring assembly ordered from Galloway Precision for next attempted fix.

Update:

Returned from factory, no explanation, invoice states, "Replaced barrel, test fired for function"

Range trip tonight, point of impact now matches point of aim. The pistol still consistently fails to feed on the second to last round from the magazine. Does not matter how many rounds are loaded in the magazine, does not matter which magazine, and does not matter which type of ammo, it jambs the nose of the bullet up against the underside of the barrel hood with the base of the case still in the magazine. Dropping the magazine allows the slide to move forward and chamber the round.

Ammo fired tonight was;

Underwood 200gr. Flat Nose Hi-Tek Coated Hard Cast
Ammo Incorporated 180gr. Flat Nose
Federal American Eagle 180gr FMJ

At this point I'm kind of at a loss of what to do. I may try sending it back to Smith for a second time or I may try respringing it. Galloway Precision now offers recoil spring assemblies for the 4" M&P 10mm, Wolff offers extra power magazine springs for the .45ACP magazines that work in the 10mm.

Original post:

I was able to get out to the range today and there are issues with the pistol that need to be addressed. The pistol was cleaned and lubricated prior to today’s range session. All shooting today was done at 10 yards except for an attempt to get a group at 20 yards with 5 rounds. Ammunition used was Underwood Ammo in the following loadings:

180gr. Full Metal Jacket-Flat Nose, 100 rounds
200gr. Flat Nose Hi-Tek Coated Hard Cast, 20 rounds
220gr. Flat Nose Hi-Tek Coated Hard Cast, 20 rounds

The following are the issues that I experienced.

Regardless of the ammunition used, the pistol consistently has a failure to feed on the second to last round in the magazine. The nose of the bullet would be jammed against the underside of the barrel hood with the base still in the magazine. Both magazines exhibited this behavior. It did not matter how many rounds were loaded in the magazine, be it 5, 10 or 15 it would always fail to feed on the second to last round. The malfunction was cleared simply by depressing the magazine release and allowing the magazine to drop a fraction of an inch, the pistol would then chamber the round and go into battery without further action, and I would then fully reseat the magazine. This happened every single time the pistol was fired.

Approximately 50% of the time after firing the second to last round in the magazine, the last round would fail to feed. This was a different type of malfunction in that the last round would be jammed straight up and down vertically between the breech face of the slide and the hood of the barrel.

Point of impact is significantly lower than point of aim with all ammunition used. It is low at 10 yards and not even on the target at 20 yards. A gun club instructor fired 5 rounds from the pistol as well and experienced the same low point of impact.

Given that I live in Alaska and my intended use for the pistol, I need it to function reliably and hit to point of aim with high performance ammunition, I sincerely want to love this pistol, but feel that I cannot rely on it in its current state. I've got an e-mail into Smith requesting a warranty return and waiting for a reply.

I'll see how it goes, but my advice is to wait a little longer for Smith & Wesson to get the bugs worked out.

This message has been edited. Last edited by: 2000Z-71,

I was a bit interested in one, but now I think you've about ruled one out for me. I've also heard other owners complain that they don't hold up well to full power 10mm loads like your Underwood.

Nothing to comment on the OP, except Welcome Back!

WTF is it with manufacturers who supply guns with sights that shoot far, far below any practical point of aim at normal handgun ranges? SIG had an absolutely bizarre explanation for doing so a little while back; I'll be fascinated to hear S&W's excuse for this.

I would pay extra for adjustable sights. Especially on guns that can shoot a wide range of bullet weights and velocities.

It sounds like that gun is on the ragged edge of tolerances with that ammo. Not sure what to think on the sights.

I had surprisingly similar issues shooting some 180gr flat point .40 S&W out of a full size competition pistol at only 1,000fps. It appeared as thought the slide was cycling too fast for the mag springs to get the rounds up, and in combo with the flat point profile, it wouldn’t feed reliably. My issue was intermittent, sometimes the first round wouldn’t feed, sometimes the 16th.

Unfortunately for your use, lower power ammo isn’t the solution.

Hopefully S&W fixes you up and it runs better. I’m interested to hear as a friend has one that works awesome.

Concerning the FTF, have you considered cleaning and polishing the followers, checking the mag body for follower hang-up possibilities, and polishing the feed ramp. Then maybe changing the mag springs. Just some ideas.

quote:

Originally posted by randyman:
Concerning the FTF, have you considered cleaning and polishing the followers, checking the mag body for follower hang-up possibilities, and polishing the feed ramp. Then maybe changing the mag springs. Just some ideas.

I'd expect a factory new gun from a major mfg to not need so much work out of the box.

quote:

Originally posted by P250UA5:
Nothing to comment on the OP, except Welcome Back!

Totally concur! Just sad it had to be about a new gun frustration.

quote:

Originally posted by randyman:
Concerning the FTF, have you considered cleaning and polishing the followers, checking the mag body for follower hang-up possibilities, and polishing the feed ramp. Then maybe changing the mag springs. Just some ideas.

I'm going to give Smith & Wesson a chance to make it right first before going down that road.

My 4” has been absolutely reliable with off the shelf ammo. I’ve yet to try the underwood or anything really full power.

One fix I have heard for the full power stuff is a stronger recoil spring. Factory is 17-18#, most are saying their reliability has gone to 100% with a 22# spring.

As luck would have it, seems the ISMI flat spring for a Glock full size drops right on the factory recoil rod. The recoil rod on the 4” is also the same as my 4” 9mm, so replacements are a call to S&W.

I grabbed a 20, 22, and 24#, eventually I’ll call smith and get a couple more recoil rod assemblies and swap springs, so Tuning will be a 2 second recoil spring swap.

Would the POA vs. POI be related to S&W assumption of bullet velocity vs. your chosen loads? I’m thinking of the 40 S&W vs. 357 Sig issue I face when shooting the P229 with one and only one sight height.

Underwood is quality ammo, however, comma, it's super hot and manufacturers cannot make guns that will function with everything from 40+p to nuclear. The fact that the pistol is reliably (pun) having stoppages at the same place in the magazine (toward the bottom where the spring tension is weaker) indicates that the slide velocity/mag tension combination is off a bit. If you want to shoot the nuke stuff reliably, you need a heavier recoil spring to slow down the slide velocity.

My M&P 10 works perfectly with everything I've put through it, but the Underwood is staying on the shelf. It wasn't reliable in my G20 or 610 (locked up the cylinder from cartridge expansion).

It is a lot to ask of a pistol to function reliably with everything from 40s&w power level loads to that rip roaring, super hot underwood stuff.

The stronger recoil spring suggestion sounds entirely appropriate.

Did you ever try a new 20# or 22# recoil spring?

Can you try some other brands of ammo before you blame the gun?

This sounds like an ammo problem to me.

quote:

Originally posted by steelcityfishanddive:
Did you ever try a new 20# or 22# recoil spring?

No, the M&P 10mm uses a dual captive recoil spring and there's nothing currently available in the aftermarket. Others with the 4.5" have used the M&P .45 recoil spring and rod from Wolff but that isn't an option for the 4".

quote:

Can you try some other brands of ammo before you blame the gun?

This sounds like an ammo problem to me.

Doubtful that it is an ammo problem. While Underwood is close to maximum pressure it is quality ammo. The same loads function just fine in my Dan Wesson Razorback 1911. Living in Alaska makes it difficult to get ammo. Can't ship ammo across Canada so we have to but from local stores. I can regularly find Underwood and Buffalo Bore, unfortunately I have not found anywhere here yet that sells Double Tap. Having bad experiences with Buffalo Bore blowing out primers, I'm basically resigned to Underwood for high performance 10mm loads.

The gun is back at Smith & Wesson for warranty repair. I'll give them a chance to make it right before I start searching for my own solutions. Not off to a good start with their customer service. They immediately agreed to take it back for repair after my initial e-mail with them. it just took 4 additional e-mails and 2 weeks to get an RMA label from them after that.

quote:

Originally posted by enidpd804:
Underwood is quality ammo, however, comma, it's super hot

I do not believe Underwood is "super hot", for 10mm, that is. I consider it to be what 10mm ammo should be. Underwood is only very slightly hotter than SIGs offerings, the FMJ and V-Crown. Ammo like Federal or Remington should be considered range/practice rounds. Guns that are truly built for 10mm should have no problem with Underwood.

You’ll never know if it’s the gun or the ammo if you aren’t willing to try other brands…

Needs a shorter front sight or taller rear sight.