Semi-auto "spitting"?

[SPE]

My apologies if this is a stupid question, but I can't seem to find a description of it online.

I've read a few posts where people have said that their revolvers were "spitting". My interpretation was that the revolver was spraying some debris from the gap between the cylinder and barrel. Given how revolvers work, I understand the concept and have experience mild cases of this with range rental revolvers.

Well, I recently bought an M&P 9, and I'm constantly being peppered by specks of some very hot material. It hits my right arm, my face, and even my left arm. (I'm left handed). I'm not getting truly burned, but it doesn't feel great, and it definitely makes me flinch while shooting, or I have to stop to brush off the hot specks.

I have an XD40 Tactical that I've shot over 3,000 rounds through with all sorts of ammo, and never noticed this issue with that gun.

I do notice that the M&P magazine and follower gets a LOT dirtier than my XD mags (which stay relatively clean), so it seems that my M&P is allowing more gases / gunk (?) to travel backwards as the case is being fired, or as it is ejecting.

I have also noticed that some of the ejected brass have black 'burn' marks that travel down the side of the case, tapering from the mouth towards the rim. But I know that some of the brass (perhaps a different brand) do not. I have not noticed these burn marks on my 40 caliber shells shot in my XD.

I've shot Blazer brass, Sellier & Bellot, Speer Lawman, and Winchester X through the M&P, but unfortunately I've only been to the range with it twice, so I haven't yet figured out if a particular brand is having the issue.


1) Is there a better name for this rather than "spitting"? (so I can try different searches)

2) Is this a relatively common issue with semi-autos, and I just never noticed it with my XD?

3) Is it that specific ammo does it more than others? (I haven't shot enough to tell if it happens more or less with different brands of ammo)

4) Is there any adjustment that can be made to the gun to remedy it, or could it require service? (i.e. chamber is too large and is causing the gases to travel backwards)


Thanks.

[taperxz]

try to pinpoint the ammo I have had that with bolt action rifles and "certain" ammo. Hopefully someone else who has that gun can chime in.

[BluNorthern]

Unburned gunpowder?

[huckberry668]

This is a dangerous situation and I'd suggest not shooting the M&P till it's been looked at by S&W. However, it sounds like an out-of-spec chamber on the M&P. Semi pistols shouldn't 'spit'. It might spits when the chamber is over sized, out of round or has excessive headspace.

Do this check, remove barrels from both the M&P and a barrel from another 9mm pistol. Take a 9mm round and put it in the barrel that doesn't spit then put the same round in the M&P barrel. Check both chamber depth and fit around the case. Check the M&P chamber being oval or have any other characteristics that the other barrel doesn't have.

Accuracy shouldn't be good from the M&P I suspect.

[Saym14]

another reason to choose the XD over the Mand P !!!

[Glock-matic]

You are most likely being peppered by unburnt powder. Iy usually means your slide is opening a bit early for the load. Try a different load and see if that helps. If it is a used pistol, recoil spring would be suspect. If it does it with different loads, give S&W a call.

[BillCA]

+1 - call S&W and let them send you a return tag for repair.

The chamber could be out of spec, but I suspect that the gun isn't locking up correctly. I've not detail inspected the M&P, but I've seen this on a 1911 with a too-long barrel hood. The rear of the barrel doesn't fit tightly to the recoil face of the slide, allowing hot gas to exit. Either the out of spec chamber or slide-fit will allow gases to dirty up the top of the magazine too.

[SPE]

+1 - call S&W and let them send you a return tag for repair.

The chamber could be out of spec, but I suspect that the gun isn't locking up correctly. I've not detail inspected the M&P, but I've seen this on a 1911 with a too-long barrel hood. The rear of the barrel doesn't fit tightly to the recoil face of the slide, allowing hot gas to exit. Either the out of spec chamber or slide-fit will allow gases to dirty up the top of the magazine too.

Thanks. I'll give them a call tomorrow and see what they say. I've heard their customer service is very good, and this seems to be an unusual / uncommon issue, so hopefully they can fix it.

Maybe I'll take it to the range one last time and see if I can notice any flames coming out of the slide port.

[SPE]

another reason to choose the XD over the Mand P !!!

Even aside from this issue (which seems to be unusual), I'm thinking the same thing.

The M&P has made me really appreciate my trusty XD.

[sirgiles]

happens to me too with unburned gunpowder.

[Phanuel]

Even aside from this issue (which seems to be unusual), I'm thinking the same thing.

The M&P has made me really appreciate my trusty XD.

I guess if you like a high bore and questionable use of redundant safeties, sure. Oh, and a $300 Croatian made pistol rebranded by an American company being sold for twice that. Love my M&P, especially with an Apex sear in it.

[tiko]

It is normal for my M&P because of its loose chamber, they made that so the M&P eats everything! The spent brass get burn marks from neck to rim!
The spent brass from my 1911 Les Baers are clean, the chambers are very tight. After 700 rds, those guns are still clean. The M&P got dirty after just 200 rds.

[Artery]

You are most likely being peppered by unburnt powder. Iy usually means your slide is opening a bit early for the load. Try a different load and see if that helps. If it is a used pistol, recoil spring would be suspect. If it does it with different loads, give S&W a call.

My PPK does that too but I've always figured since its a blowback pistol the slide is opening more or less "immediately" so I should expect it.

[SPE]

I guess if you like a high bore and questionable use of redundant safeties, sure. Oh, and a $300 Croatian made pistol rebranded by an American company being sold for twice that. Love my M&P, especially with an Apex sear in it.

Those lame excuses are the best you can come up with? You've been trolling on Glock Talk and MP-Pistol too long. By that same weak logic, Sigs, CZs and all 1911s suck.

Ironic considering you proudly mention the Apex sear, which is virtually required to compensate for the horrible M&P trigger.

[Phanuel]

Those lame excuses are the best you can come up with? You've been trolling on Glock Talk and MP-Pistol too long. By that same weak logic, Sigs, CZs and all 1911s suck.

Ironic considering you proudly mention the Apex sear, which is virtually required to compensate for the horrible M&P trigger.

http://m4carbine.net/showthread.php?t=37731 Enjoy. 1911s do suck, but people love spending money and paying smiths to make them work. They are a legendary handgun, but not combat handguns. (I'll get a lot of flak for that as well)