M&P9 barrel saga

[Trajan]

I don't know.

It would be interesting to dig a little further into the pitting issue, honestly. You know, I'm teaching an engineering forensics class this summer...

I'd say you M&P fans have a three pipe problem on your hands.

It would be a very interesting if you did.

Is this a random issue, or an almost guaranteed issue? IIRC Defoors Glock 17 went 200k+ with just some spring changes and a second set of sights before the barrel wore out. Not sure what the breech looked like.

[JV_]

IIRC Defoors Glock 17 went 200k+ with just some spring changes

I think there's more to this than springs. This thread has been moved or deleted since I copied it (01-13-2012), but the URL used to be:
http://www.m4carbine.net/showthread.php?t=96530

Question to Kyle Defoor:

...how many malfunctions you had, how long it took to reach 200k rounds, etc?

Answer:

Malfunctions- I honestly don’t know. Just the normal stuff like when you break trigger springs and slide release springs. I think there was one squib round in there, the rails had to be replaced a few times, a number of extractors, etc.

I'm not sure how the rails on Glocks are replaced without changing out the whole frame, after-all that's what they did with the E series guns that had a rail defect - complete frame swap.

[Tamara]

...M&P fans...

Weird. That's like being a... I don't know... a Mr. Coffee fan.

[Trajan]

I think there's more to this than springs. This thread has been moved or deleted since I copied it (01-13-2012), but the URL used to be:
http://www.m4carbine.net/showthread.php?t=96530

Question to Kyle Defoor:


Answer:



I'm not sure how the rails on Glocks are replaced without changing out the whole frame, after-all that's what they did with the E series guns that had a rail defect - complete frame swap.

Oh wow.

I found a post on his website mentioning it (he didn't mention the rails though): http://www.kyledefoor.com/2010/03/well-i-did-it.html

[JV_]

(he didn't mention the rails though): http://www.kyledefoor.com/2010/03/well-i-did-it.html

It also doesn't mention the extractors. I'm kind of surprised to read it only had 2 recoil springs. I wonder if that's a typo?

The ole girl has had 2 sets of sights, 2 recoil springs, and 8 trigger return springs.

[Trajan]

It also doesn't mention the extractors. I'm kind of surprised to read it only had 2 recoil springs. I wonder if that's a typo?

That's what I was thinking, but then again, maybe that's why he had to replace his rails?

[ralph]

The agencies that have reported the worst pitting issues mandate lead-free training ammo (both lead-free projectile and primer).

DocGKR:

Why do the lead free bullets and lead free primers cause more pitting issues? How many rounds does it take to cause damage?

[BLR]

DocGKR:

Why do the lead free bullets and lead free primers cause more pitting issues? How many rounds does it take to cause damage?

DDNP priming mixture.


Number of rounds would depend on a number of things.

[Greg Bell]

My G19 has some pitting on the breech face. I pretty much blame it for my occasional FTFs. On the other hand, it is an 89 model with original "non recall" recalled parts so it has earned its character lines.

[Lomshek]

Anyone here have a 8-10" gun they want to try an experiment with?

Bill, I'd be up for loaning a gun (or three). The first M&P I bought which is about 3 years old has some common problems. Horrible accuracy with some loads, radically different POI for the same POA and some sketchy "high above POA" impacts. I'd have to do some digging to see if I saved the test case envelope with date on it. None of the ones below are quite 10" guns but they're far from what I'd call acceptable accuracy and have no consistency between loads.

All guns shot below are various M&P 9 FS's with thumb safety. One target includes a group I shot with my Ruger P94 which I've had for years and has about 75K rounds through it and a few groups with a Ruger 22/45 which I know to be an accurate gun to show what I'm capable of (2" or so 10 round groups at 25 yards).

All groups are 10 rounds fired from a rest at 25 yards by me with a dead center hold (top of front sight post centered on the target center dot). I hosted an AFHF a couple years ago and am in no danger of winning any trophies but can shoot fairly well.

Here's a photo of some test targets I fired after missing a number of shots on a 35 yard USPSA classifier I called as good shots. Those misses started my investigation into what was the gun and what was me.

Original barrel on original M&P (Ser# MRE). The left-most target was shot with a Ruger 22/45 and P94 to compare.


Replacement barrel on original M&P (Ser# MRE).


So in a funny twist the new barrel shoots WWB to POA and in a near respectable 5 1/2" group but HST 147 and Ranger 127 (plus my handload) to 5" - 7" groups and nearly 6" above POA.

I've since bought a second gun and my brother in law has as well with targets below.

Ser # DXE


Ser# HBK. Far left target is the Ruger 22/45 for a control group.


I'm at the point I was going to buy a spare locking block, weld it and the barrel hood up and recut everything for a tighter fit and longer lock up to see what it would do as well as crown the barrel.

I was also planning on installing an Apex FSS kit to see how much of the problem is the M&P curved trigger & pull which does not seem conducive to me shooting my best groups. As of now everything is pure factory.

The gun has gone to the factory twice for a new barrel about a year ago. The first replacement barrel didn't have the leade cut properly (or at all) so longer rounds like the Ranger 127 +p+ wouldn't fully chamber.

ETA - One thing that is clear is the complete lack of consistency from gun to gun in what shoots well or poorly and what POI a given load will shoot.