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Old October 20, 2013, 02:10 PM   #1
Koda94
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Sig 938 failure to feed tips?

Brand new Sig938 extreme

3 failure to feed issues within about 100 rounds first time out, two while racking the slide and one while firing. Its looking like the bullet is taking a nose dive when the slide goes to chamber it then the nose of the bullet wedges itself on the feed ramp and everything comes to a stop.

this happens with FMJ, Corbon 124g +P BHP, and even Hornandy Critical Defense 115g FTX (which has a more tapered bullet tip I would think feeds better). Replicating the problem it seems the first round in the 7capacity mags is a problem child. Should I get the barrel ramp polished?


tips or solutions would be appreciated.
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Old October 20, 2013, 03:05 PM   #2
ttarp
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My advise would be to shoot it a little more before you decide anything. I wouldn't worry too much about the failures when racking the slide, the failure while firing would cause more concern. Give your pistol some more range time and see if things smooth out.
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Old October 20, 2013, 03:47 PM   #3
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Just out of curiosity, did you clean and lube your new gun before taking it to the range?

It has been my personal experience years ago that not doing this can lead to malfunctions. When I was younger and didn't know any better, I would just take a new gun out and shoot it. The grease, gunk, etc from the factory can cause all sorts of issues.

Also, it is not uncommon for some guns to have issues in the first couple of hundred rounds. This is the break in period, and this is when the part's surfaces wear in together.
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Old October 20, 2013, 06:18 PM   #4
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That it happens with FMJ is interesting.

Honestly, if it continues call SIG. It's a new gun, it's not your responsibility to troubleshoot it. If you do contact SIG, please let us know what they say. My experience with SIG CS is that lately they love to blame ammo for just about any problem under the sun. Don't be too timid to push the issue if need be.
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Old October 20, 2013, 07:50 PM   #5
mas4489
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I purchased a Sig 938 recently, put about 150 through it so far... No issues
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Old October 20, 2013, 08:22 PM   #6
bilbo1907
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sig 938

No one blames the magazine? My first move would be to slightly alter (spread) the feed lips to present a higher angle of attack.
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Old October 20, 2013, 08:41 PM   #7
Koda94
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Quote:
That it happens with FMJ is interesting.
I should clarify, it did happen with a FMJ but only one time and after about 50 rounds the feed ramp was dirty. The problem is there but I cant seem to replicate the issue anymore with FMJ only HP's. Since then I have cleaned and lubed the gun...

I didn't clean the pistol that day, I inspected it including field stripping and nothing seemed dirty or oddly lubed. I do regret not paying closer attention and cleaning it before the first time out.

Quote:
No one blames the magazine?
actually I am suspecting the magazine because I cant seem to replicate the problem in my 6 rounder. I'm skeptical about altering/modifying any magazine right now because like TunnelRat said its a new gun and not my responsibility to trouble shoot it I pretty much agree with that. I don't think after spending the amount these things are selling for I should have to do anything including the magazines.

its odd to me just how much the cartridge is pushed down into a nosedive before hitting the ramp. I don't know if this is usual since never an issue in any other auto pistol.

Unfortunately im a recession shooter and also struggling to find premium SD ammo of most any brand so qualifying and SD ammo is a big deal. I do plan on shooting it a little more before making any judgment but it may be a while before I get back to the range. I'll remember to follow up when I do.
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Old October 20, 2013, 09:50 PM   #8
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I have heard issues before with HPs feeding, most often Hornady (I have my flame suit ready). With two types though is interesting.

If it really only was one magazine, than that might be the issue. 50 rds shouldn't be enough to dirty the feed ramp to prevent feeding, unless maybe you were shooting soft lead ammo. You might try calling SIG, saying it was with one magazine (so you think) and ask them to send you another. This lets you keep testing without having to send the gun in. And if it does work then it's a relatively easy fix.
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Last edited by TunnelRat; October 20, 2013 at 11:30 PM.
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Old October 22, 2013, 06:56 PM   #9
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If it's always the top round in the mag, then I'd look at the mag. I've had issues with fully-loaded mags, especially those designed to hold "one more round", with excessive spring pressure on the top round adversely affecting feeding; the round tends to nosedive and stump against the frame rather than feeding up and into the chamber.
Sometimes it's a bit of a tightrope walk, as you need enough spring pressure to get the last round into position, without too much pressure on the first round.
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Old October 22, 2013, 08:59 PM   #10
Koda94
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Quote:
Originally Posted by RickB
If it's always the top round in the mag, then I'd look at the mag. I've had issues with fully-loaded mags, especially those designed to hold "one more round", with excessive spring pressure on the top round adversely affecting feeding; the round tends to nosedive and stump against the frame rather than feeding up and into the chamber.
Sometimes it's a bit of a tightrope walk, as you need enough spring pressure to get the last round into position, without too much pressure on the first round.
This seems to be the problem and with the 7 rounders not the 6. I inspected them to each other but cant see anything wrong or otherwise know what to look for they are all identical up top.

Thanks for the tip I will check out functioning with only 6 loaded in the 7 rounders and see if that solves it. Your description fits my situation.
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Old October 22, 2013, 09:14 PM   #11
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If it does solve the problem, give Sig a call. I have dealt with their warranty department before and they were great. They will send you a new magazine if that is causing the problem.
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Old October 27, 2013, 09:06 PM   #12
Koda94
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Quote:
Originally Posted by RickB
If it's always the top round in the mag, then I'd look at the mag. I've had issues with fully-loaded mags, especially those designed to hold "one more round", with excessive spring pressure on the top round adversely affecting feeding; the round tends to nosedive and stump against the frame rather than feeding up and into the chamber.
Made it out to shoot today, this is definitely the problem. Tested this by removing the first (fully loaded mag) round and all seem to load/feed fine including hollowpoints. If I put a hollowpoint in as the top round, it nosedives and jams up against the feedramp roughly every other time (case rim snags the case groove on the next round causing it to pivot down...). Fired 100 rounds of FMJ from fully loaded mags and not one failure to feed. Further testing shows the same results in all my mags: 3x 7 rounders and 1x 6 rounder all factory Sig mags.

Due to the expense and availability of premium hollowpoints in my area I have not been able to fully test any one brand with live fire enough to qualify for SD use. Because of this I am also not confident the problem would not persist even with the second or other round counts in the same mag with JHP. Testing at home (safely of course) I think I could qualify JHP rounds loaded with one less or a FMJ as the top round (I do not like mixing SD ammo...) but ideally I need more range time with expensive JHP to qualify that idea. (The concern here is if I needed a tactical reload in a self defense situation)

in short, gun shoots fine I am confident its a mag issue. Any ideas for solutions? Should I call or send all my mags into Sig?
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Old October 28, 2013, 04:24 AM   #13
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Take another range trip. Load your mags - 1 round and shoot several mags. If you still have problems call Sig.
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Old October 28, 2013, 08:29 AM   #14
Garycw
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Sig 938 failure to feed tips?

It very well could be partly a mag issue, but typically I always like to polish the feed ramp on All semi autos. Everything runs smoother, especially with HP's. it's solved similar issues on a few of mine quite well with zero feeding problems. The first round was always the issue with mine. A dremel with felt tip and polishing rouge will give a mirror finish without changing angle.
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Old October 28, 2013, 10:51 AM   #15
tirod
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Are the slide rails greased or oiled?

FTF is caused by excessive friction, as said, the first three rounds to do so, two were when manually racking the slide. That implies a fully loaded mag pressing up underneath, which would cause friction there, and with the slide rails. There is also the question of how far back the slide is held before release, and whether plated cases or bare brass are being shot.

Self loading firearms in general all have those issues, whether a P938 or AR15. I did that with both in the last ten days. I don't count FTF when loading the gun as a weapon design issue when it successfully feeds the action with full power rounds. There are completely different levels of force involved.

Mine happened with dry guns that both needed cleaning, and I got the expected results. There are less than 100 rounds thru either.

Polishing the feed ramp helps the nose to slide up into the barrel, but there are also friction points inside the mag at the lips, and on the underside of the slide where it depresses the next round before it pops up the last bit to get pushed by the breech. And, as said, it also goes to the ogive angle of the round and what it's made of, too. Lots of little details in feeding can cause it, and the old saw about shooting it really means that a lot of the freshly machined surfaces that contact the rounds need to have the friction points knocked down, just like a trigger. We really do have to break them in, same as an engine in a car.
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Old October 28, 2013, 11:46 AM   #16
RickB
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Quote:
It very well could be partly a mag issue, but typically I always like to polish the feed ramp on All semi autos. Everything runs smoother, especially with HP's.
Does the 938 have a steel frame? You generally do not want to polish aluminum frames, as it removes the protective coating, whether it's anodizing or plating, or a modern slick polymer finish, and frame damage can result. I've never had issues with frames that didn't have heavy tool marks; if there are no grooves or other obvious imperfections that might catch the tip of a bullet, then it's smooth enough.
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Old October 28, 2013, 11:53 PM   #17
Koda94
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Quote:
Originally Posted by tirod
....And, as said, it also goes to the ogive angle of the round and what it's made of, too. Lots of little details in feeding can cause it....
lots of good detail in your post Tirod makes sense to me, but in my laymans mind I just want it to work from the beginning.... however, I really like this pistol but don't want to jump the gun (pun intended) if all it needs is a breaking in period to smooth out those friction points.
I've been storing the mags fully loaded as well as (safely) chambering hollowpoints over and over again. The gun is properly lubed and cleaned but even immediately after last weekends range time (dirty gun) I've noticed the hollowpoints are feeding reliably more than not. I suspect overall I am finding my own solution. I need to swap out the hollowpoint selection set with ones never chambered and see (but my premium ammo cache is dangerously low...).

RickB, I think the frame is aluminum but the feed ramp on these pistols is 100% part of the barrel component and can be polished, which I might consider.
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Old October 29, 2013, 04:38 AM   #18
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The last thing you need is to void the warranty at this point. If the feed ramp needs work, let Sig do it.
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Old October 29, 2013, 09:43 AM   #19
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I didn't see if you tried multiple 7 round magazines. You did note that a 6 round mag doesn't cause the issue.

My P938 works great with the 7 round mags. IMO, before you mess with ANYTHING you should call Sig. Maybe they'll send you another mag to try. Maybe they'll want to have a look at it.

You bought a not inexpensive pistol... one backed by a good company with a good warranty. My advice would be to take advantage of that- Sig wants you to be happy with the firearm. I'd give them the chance to make that happen before doing anything more than a good cleaning/lubing.
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Old October 29, 2013, 11:10 AM   #20
tirod
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I just tried to duplicate this, and ran across some points:

With the mag in, loaded with 7, and the slide lever engaged, using Hornady CD. Tripped the lever, the cartridge nose dived into the ramp, where the flat nose with the plastic plug hit at nearly 90 degrees to the ramp. Got it to chamber, ejected, second round goes right in.

Reloaded, 7 in, pulled the slide back fully and released, it chambered.

A primary thought is that the little extra rear movement is adding enough momentum to keep the round from nose diving.

From the owners manual: 3. Pull the slide back fully and release, allowing the slide to fly forward. In the section on reloading when the slide locks back: 5. Release the slide by:a. Pressing down on the slide stop or, b. Pulling back on the slide and release

Other guns are noted for having issues using the slide release when loading, Glock comes to mind. It's been said you must rack the slide to load the first round. Using the slide release may cause it to jam. These guns may have a slide release, but SIG isn't saying you can use it to load the gun in every situation. Just as with other guns, it's dependent on the round, the gun, and the operator. Sometimes it works, sometimes not. No guarantee.

Along with all the loading and ejecting, I'm picking up scratches down the length of the cases from something under the slide. If it's marking it, it's a friction point. The cartridge is crimped, which is keeping the round from setting back.

What we may be experiencing is a combination of spring tension in the magazine spring, the recoil spring, and how things can change with just a half inch of slide travel. I speculate this may not be as likely with round nose FMJ.

That experiment remains for tonight, I've got a floor to tile.
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Old October 29, 2013, 01:11 PM   #21
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Quote:
From the owners manual: 3. Pull the slide back fully and release, allowing the slide to fly forward. In the section on reloading when the slide locks back: 5. Release the slide by:a. Pressing down on the slide stop or, b. Pulling back on the slide and release
+1 to this. If you are experiencing failures to feed while racking the slide, the majority of the time it is user error.
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Old October 29, 2013, 07:38 PM   #22
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Sig 938 failure to feed tips?

One other thing I do with the Hornady CD. Rounds is trim the tip a little to make sure its flush and does not protrude in the slightest. The plastic tip is a good idea, but I've found some of them want to grab the ramp a little when chambering first round sometimes. A razor blades works good to trim tip if needed

Last edited by Garycw; October 29, 2013 at 08:05 PM.
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Old October 29, 2013, 08:50 PM   #23
tirod
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Correcting the idea there is a half inch difference, it really looks more like 3/16ths of an inch from being parked on the slide stop and full retraction.

Hard to argue -the three major stoppage causes are mags, ammo, and the user. These are brand new mags, doubt they cause the problem. A single stack mag is pretty simple. Ammo, maybe. The user (with four fingers pointing back at me,) sure. New owner, new gun, things to discover and learn. Like, don't bend the ejector reassembling the gun, don't flip the safety on with the slide off, etc.

One gun isn't the same as the next, despite the similarities. We sometimes work the actions in expectation they are "all the same," reality proves different on occasion. It's why it's said to stick to one type of trigger operation, etc. Hard to remember and operate them under stress when you have a different firearm in your hand daily.
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Old October 29, 2013, 09:27 PM   #24
Koda94
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some good tips in here much appreciated.

Couple notes: If I decided it was the gun I would have Sig do it, not gonna polish the ramp myself. I never release a slide by its stop, and am aware to not follow the slide forward after releasing it. I'll have to check my owners manual I am surprised to read they say to use the slide stop....

Overall I'm confident this is just a break in period. I need more range time with hollowpoints but the top round is feeding almost 100%. I had one last night that paused... I feel as if whatever it is is smoothing itself. Now if I can just afford and find some hollowpoints I'll be doing good.

I suspect its the mag springs, the last (top) round is a pain but getting easier as is its chambering....
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Old November 1, 2013, 10:19 AM   #25
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I finally pulled out a box of old PMC 124 gr FMJ roundnose.

Grabbed the calipers, it measures about 1.160, the Hornady CD measures 1.090, which is .070 shorter.

The first round of FMJ will load either by slide stop or full slide retraction. Looking in the port, the round sits nearly against the feed ramp, vs the Hornady sitting further back. Pushing the first round down, it stays more level and the round nose isn't at a harsh angle.

This is consistent with the history of 1911's, roundnose is the standard, civilian hollowpoints or competition wadcutters jammed. It caused a lot of fluff and buff back in the '90's before Keltec owners invented the phrase.

Just shoot 500 rounds thru it - somewhat an internet cliche, but at that point it's either running or definitely balky.
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