Help diagnosing M&P fitted barrel malfunctions

[jumpthestack]

I have a Storm Lake fitted barrel for an M&P9. The accuracy is much improved from the stock barrel, but I get a lot of malfunctions. I never got malfunctions with the stock barrel.

There are 2 main malfunctions.
1) The round hangs up horizontally going into the barrel.
See pictures:




Pushing the back of the slide forward does nothing, but if I smack the bottom of the magazine upward, that's usually sufficient to jolt the round up so it goes into the chamber. Also pulling the slide backward slightly and then letting it slam forward also fixes the malfunction. This happens about one every 50 rounds or sometimes more. This seems to happen more frequently with hotter ammo, I've noticed when trying different powder charges in my reloads.

2) Upon having these issues, I consulted the gunsmith who fitted the barrel, and he said the chamber was set up for 1.10" OAL rounds, and since I was shooting 1.15" OAL rounds, there were problems. He reamed the chamber out further. When I received the barrel back, I still had the original issues, plus now I started having occasional failures to fire(light primer strikes). This happened about one out of 30 rounds. If I put the round with the light strike back in the chamber, it always fires on the second try. After I started having the light strikes I replaced the recoil spring and striker assembly at which point the rate of light strikes dropped to about one every hundred.

I'm mostly shooting my reloads, and something might be wrong with them, but they work fine in the stock barrel and in my Beretta and Glock. With the fitted barrel, I had the same malfunctions at a lesser rate after shooting about 200 rounds Sellier and Bellot 115gr, and I shot 50 rounds of American Eagle 115 gr with no problems, 50 rounds PMC 115 gr with no problems, and 50 rounds Remington 115 gr with 1 failure to feed. I don't really want to buy a whole bunch of commercial ammo to test things but suffice to say I do get malfunctions with commercial ammo, albeit at a lesser rate.

When I switch back to the stock barrel, all the problems go away but the accuracy is also much worse.

Ideas?

[CCT125US]

Are you checking your handloads in a case gage?

[gringop]

My SWAG is that the Storm Lake chamber is a bit tighter then the factory, and any non perfectly reloaded ammo is causing the issue. My days of chamber checking my reloads are behind me since I picked up a Lee Factory crimp die. No more bulged cases, no more malfs, no more rejects that wont drop in and drop out of the chamber.

Gringop

[Chris Rhines]

SAAMI max overall length for the 9mm Luger is 1.169". If your gunsmith is telling you that the barrel was set up for 1.10" cartridges, I'd suspect him of blowing smoke up my kiester.

My jackleg diagnosis is that the barrel was never properly fitted. When the barrel is unlocked, it's either too high up or too far back for the cartridge to make it into the chamber. The photo that you attached seems to show a round jammed against the top of the chamber - that indicates to me that the barrel isn't descending far enough out of full lockup.

Reaming the chamber too far out could also be the cause of your light strikes. If the chamber headspace is too great, the firing pin strike can push the entire cartridge forward, instead of crushing the primer like it's supposed to.

I don't know who your gunsmith is, but I would recommend finding a new one.

[jumpthestack]

Are you checking your handloads in a case gage?

Yes, they all go in and drop out in a LE Wilson case gage. I just hand cycled a bunch of rounds through and when the malfunction happened, I took those rounds and case gaged them. They dropped in and out smoothly. When I tried the same round a second time, it did not seem more likely to cause the malfunction again.

[ToddG]

I don't know who your gunsmith is, but I would recommend finding a new one.

This.

[jumpthestack]

SAAMI max overall length for the 9mm Luger is 1.169". If your gunsmith is telling you that the barrel was set up for 1.10" cartridges, I'd suspect him of blowing smoke up my kiester.

My jackleg diagnosis is that the barrel was never properly fitted. When the barrel is unlocked, it's either too high up or too far back for the cartridge to make it into the chamber. The photo that you attached seems to show a round jammed against the top of the chamber - that indicates to me that the barrel isn't descending far enough out of full lockup.

Reaming the chamber too far out could also be the cause of your light strikes. If the chamber headspace is too great, the firing pin strike can push the entire cartridge forward, instead of crushing the primer like it's supposed to.

I don't know who your gunsmith is, but I would recommend finding a new one.

Yeah, that's what I was afraid of. BTW I noticed that if I slowly ride the slide forward, I can induce this malfunction every time with the fitted barrel and S&B ammo. Doing the same thing with the same ammo and stock barrel, it always goes into battery.

[YVK]

I think that Chris is absolutely correct. This looks like a classic 3 point stoppage well known to those who played long enough with 1911s. My knowledge of gun's mechanics is almost embryonic, but these are usually caused by incorrectly fit/timed barrel, even though people like blaming it on OAL.

[klewis]

I know nothing.

That said, I wonder if the weight of the RDS + new barrel that maybe wasn't fitted so well is throwing off the slide cycling. Perhaps a slightly heavier recoil spring to that big boy back in battery would help?

[PPGMD]

IIRC only one company/person is doing Storm Lake fitted barrels. So if this was done by who I think it was, he isn't a well known gunsmith.

I have seen the results from his barrels and have been tempted to send my latest M&P 9 Pro in, but I think I will continues to wait for Apex's barrels. I just Scott, and Randy much more as they have rather well known gunsmith credentials.