New SIG P938 malfunctions: ideas?

Brand new guns sometimes need breaking in and a good cleaning.

1KPerDay said:

It's clean and lubed. I guess we'll run a couple hundred rounds through it and see how it goes. The FTEs are what concerned me most.

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Did you try more than one brand of ammo?

Take the mags apart and clean them too.

Recently got a new 938 that I haven't shot yet. What I have heard and read is that they need a fairly extensive break in (200 rounds seems to be the number). I knew this going in so I'm prepared for it. Have been doing a lot of dry firing and the trigger seems to be crisper without the creep that it had when I got it.

That's better than what happened to my Dad. Firing pin retainer (I think the part is called) fell out and locked the slide back. He sent it to Sig, they said "it MUBAR" and sent him a new one.

I'm paraphrasing the conversation, of course.

I like my P938. It was a very tight gun from the factory, and here is my suggested break in. Load the magazine(s) as soon as you get it (them) and let it (them) sit until you use it (them). Clean it and liberally lube it, including the top of the barrel hood. Rack the slide a couple of hundred times. Clean the rails and hood again and liberally lube it the same way. Chamber a round if safety conditions permit so the extractor gets some tension on it until you finally shoot it. Shoot 124 grain full power ammo. Don't shoot it for extended shooting sessions unless you check it and it still is wet. I have had 5 malfunctions in mine, 4 from Wally World Winchester white box 115s. 3 were in the first magazine. I had one malfuntion with a Speer 124 gr. Gold Dot, and that was at about round 160. Since then, it has gone 250 124 grain Gold Dots and Blazer aluminum with no trouble.

I recently picked up a 938. 500 rounds through it now. Not one issue whatsoever.
Blazer FMJ, Cheap white box Federal FMJ, Magtech FMJ, Hornady Critical Defense.
All in 115's. Trust it enough I carried it today.

did you have any failure to extract?

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Yes, 3 in the first magazine with 115 WWB, one at around round 60 with the same ammo, and 1 at round 160 with a 124 Gold Dot. I started using the TW25B (that was in the sample pack in the box with the gun) and Break Free, and shooting 124 Blazers and Gold Dots, and no more failures to extract.

The breakfree is what I use too. Did you take the mags apart and clean?? Since everything is ejection related besure there no burs or crud on or around the ejector . This trick has worked for me and others of decades. If you have a battery drill and some metal polish or jbs take a nylon bore brush and put it in the drill and wrap enough cotton patch around it to make a tight chamber fit and with the polish give the chamber and slow in and out for 10 seconds max. It will clean off any sharp edges during chambering and not hurt the chamber. Clean well and see if that stops the FTE. Use some 124gr for a while too. Try HP after you run a couple hundred fmj first. I have allways had good luck with magtec ammo for break in.

There are ALOT ALOT of guns (yes i said it twice).... With a Fail To Extract issue where the round fails to get out of the chamber and the next round gets jammed up behind it.

I called SIG Customer Support on mine. Here is what they told me:

"90% of the guns we get in with FTE issues, we cannot duplicate. We believe it is recoil sensitivity of the shooter."

YMMV.

Didn't SIG initially blame the P238 problems on the shooters as well? Turned out to be a recoil spring problem, mostly.

It seems pretty obvious that there is a flaw with the extractor design and setup on the P938, but SIG is doing the "blame the customer" thing again. I sort of suspected this was going to happen with the change from an internal extractor on the P238 to an external extractor on the P938; they are also having problems with the longer extractors on other P-series pistols.

Shocking. My extractor was so long that in its MOST open position possible, that the spec Base Diameter of a 9mm cartridge (.392") was .004" wider than my maximum open position.... FOUR THOUSANDTHS.

SN13 said:

There are ALOT ALOT of guns (yes i said it twice).... With a Fail To Extract issue where the round fails to get out of the chamber and the next round gets jammed up behind it.

I called SIG Customer Support on mine. Here is what they told me:

"90% of the guns we get in with FTE issues, we cannot duplicate. We believe it is recoil sensitivity of the shooter."

YMMV.

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Yea, post #12 looks like it was because "the shooter was recoil sensitive". not

Obviously a Failure for the claw to drag the casing out of the chamber is a result of limp-wristing it! We all know that! :banghead:

1KPerDay said:

Wild. However, why does a "too-long" extractor fail to rip the case out of the chamber? Is the rim camming the extractor outward too far so that the inside rear edge of the extractor is angled forward slightly or something?

Just trying to wrap my mind around this. If anything, my caveman brain says that if the extractor is too long (and the round chambers with the extractor in the rim properly) it should work TOO well, and maybe hold onto the case after the front clears the chamber or something.

Thanks for your help.

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Good Question.

All the casings I pulled out that Failed to Extract, looked as though the extractor scraped the rim from the base forward to .002" from actually jumping the rim. It was as if the extractor never made it completely over the rim and was just jabbing into the side. THAT would cause a FTE. That was my initial assumption.

Here is a Professional Artist's Rendering.

That's how my mind imagined it. Nice drawing.

I wonder what percentage of the P938 pistols out there have this issue? May need to be addressed before I plunk down nearly $700 for one.

Now, keep in mind that a 9mm rim base within spec should be:

Rim diameter 9.96 mm (0.392 in)

(SEE 9mm Wiki for more measurements)

0.392 Inch Diameter. My Extractor measured .388" from the claw to the other side of the breach face (AT maximum open).

I'm sure that most 9mm casings are .392" or less within some specified range. The FEW casings that were at the high-end of within spec, were having the issue (assumption).

You can see all my measurements here: http://www.thehighroad.org/showpost.php?p=8359968&postcount=29

I called SIG Customer Support on mine. Here is what they told me:

"90% of the guns we get in with FTE issues, we cannot duplicate. We believe it is recoil sensitivity of the shooter."

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That just makes me angry when I read something like that. I'm very happy with my non-railed CPO P229, but I can't see myself ever buying another Sig. The way that company has been run over the last 6-8 years makes me sick.