Feeding issues revisited

[Sarge]

Different gun since the culprit was scheduled to be refinished and I sent it off. Go figure! But one pic shows pretty close to what the jam looks like and the other shows the presentation from the mag. As you can see the rounds are pointed right at the chamber so I'm still inclined to believe there is something happening to drag a second round forward. I measured my feed lips and they are all pretty consistent but wider than the Atlas video mentioned. Mine are .360 in rear and between .365-.370 in front. So they certainly should not be nose diving as a mag issue?

[Sarge]

I haven't heard many complaints about the MBX mags, what are you hearing? Perhaps I'm just sensitive to guys asking about their MBX mags not working and others always respond Adrian will take care of you. All things considered mags are a pretty simple device and should be 100% especially by now. Seems to be a few threads on these forums about problems with springs, followers, etc?I'm thinking about order a couple in the next few weeks. Either that or just get STI bodies and build a couple.

Anyway, the fact that it only happens in a match makes me think it's your grip. (as in how you grip it) You must be doing something under pressure that is causing it. I can't imagine that would be a problem with a steel grip that it had on it? Besides, my other gun gets gripped the same I would assume and it's got several thousand through it without any stoppage currently. Could it be the gun is running better as it gets hot? First stage of the day. Fired two rounds and jammed. Dropped the mag and fired almost a full mag and jammed. Dropped that one and fired a few from the third mag and it jammed on the last shot of the stage. For me in practice my gun will stay hot as I run drills and never has time to really cool off. In a match you shoot 20-30 rounds then don't shoot again for a hour. I'd be trying to duplicate it in practice, in hopes that would help me determine the problem. I took it to the range three days before the match and it ran several hundred hot, cold, slow fire, mag dump, holster and shoot other guns, 10 minutes later still ran perfect.

Have you tried a heavier recoil spring? I have always ran an 8 pounder. As tight as the mag is stuck in there after the jam tells me there is plenty of spring tension? Take on the buffer if you have one? No buffer

I'm not trying to shoot holes in any ideas. Believe me I need and appreciate everybody's suggestions and opinions. It just doesn't seem rational to me that this gun won't work after performing so well for a solid year.

[zzt]

Sarge, I'll say this anyway just in case it helps, although since you are using multiple guns, I don't know.

I had a similar problem with my 40 Open pistol a while ago. I was happy with my MBX mags and decided to order another one. I could not get the new one to run reliably. Same problem as you, but only in a match. It jammed anytime I tried to run the gun fast. I eventually discovered they had mistakenly put a 9mm follower in instead of a 40. The 9mm follower, being less wide allowed the 40 round to cock the follower and sit lower in the mag. It had also allowed the spring to take a set to the left, so it was increasingly common. I sent the mag back to MBX with a note. They replaced the spring and follower with the correct one and sent the mag back along with the original spring and follower. It runs like a top now.

The slide was actually outrunning the mag's ability to push a round up in time, because it sat lower in the mag to start. Have you replaced the recoil spring lately? If it was a little heavier than the last one, the slide may be short stroking a tad. That may cause the slide to move forward before the next round is high enough for proper stripping.

If it's any consolation, I have the same problem with my Buckmark Open gun, except they are nose up jams that jams the mag in the gun and is a bear to clear. I can clean the gun, run it dirty or in between. I can simulate a match and run multiple 10 shot strings with splits in the .15 to 1.8 range and never have a problem. I can shoot it an hour before a plate match and have no problem. But every time I shoot a match it jams, and it jams on every string. Only in a match, so it has to have something to do with what I do in the match. I just haven't figured it out yet.

[tyler2you]

AFTEC or standard extractor? Could excess extractor tension be slowing the round sliding up the breach face and then the slide gets too far forward on the round before it's high enough on the breach face?

[ChuckS]

Sarge,

Take a look at how the ammo stacks in the mag.

If there a gap between the top and second round (arrow), the top round will dip its nose when getting pushed forward by the slide. When that happens, it is up to the feed ramp geometry to save the day. The mag may work in one gun but not another. It may work in slow fire but it chokes at match shooting rates. You can mess with the feed ramp, but if you have a gap in the stack, the issue is likely in the mag where it transitions from double stack to single stack.

I learned that from a guy named Beven,

Good Luck!

Chuck

[superdude]

AFTEC or standard extractor? Could excess extractor tension be slowing the round sliding up the breach face and then the slide gets too far forward on the round before it's high enough on the breach face?

The extractor is not involved in nosedive jams because the rear of the case has not started to slide up the breach face yet. That doens't happen until the nose of the round starts to enter the chamber.

[superdude]

Sarge,

Take a look at how the ammo stacks in the mag.

Stack_Up_2.jpg

If there a gap between the top and second round (arrow), the top round will dip its nose when getting pushed forward by the slide. When that happens, it is up to the feed ramp geometry to save the day. The mag may work in one gun but not another. It may work in slow fire but it chokes at match shooting rates. You can mess with the feed ramp, but if you have a gap in the stack, the issue is likely in the mag where it transitions from double stack to single stack.

I learned that from a guy named Beven,

Good Luck!

Chuck

Correct. Look for the gap. I've seen some folks who have a gap in STI mags, but I don't have much hands on experience with them. The gap allows nosedive.

Para ordnance has 2 different designs for the 38 super and 9mm magazines, the 9mm magazine reduces the gap. It is described here: http://38super.net/Pages/Para%20Magazines.html

[superdude]

With single stack guns, one way to reduce nosedive a little is to have the magazine sit a little higher in the magwell. EGW makes a special magazine catch for this purpose. I don't know if one is available for double stack guns.

You could put the mag in your different guns and check for how high it sits when locked in place. Look for the position of the cartridge base relative to the bottom of the stripping rail in breach face. If it is sitting a little lower in your troublesome gun, that could contribute to the problem.

There are many factors that contribute to nosedive and it can be difficult to troubleshoot. With luck, everyone's advice will get you pointed in the right direction for a cure.

[tyler2you]

AFTEC or standard extractor? Could excess extractor tension be slowing the round sliding up the breach face and then the slide gets too far forward on the round before it's high enough on the breach face?

The extractor is not involved in nosedive jams because the rear of the case has not started to slide up the breach face yet. That doens't happen until the nose of the round starts to enter the chamber.

I wouldn't be too quick to discount the extractor. Most everything I've read indicates that the case rim is entering the extractor groove at an angle as the round contacts the ramp, not when it's already entering the chamber. Here's one discussion:

http://aegisacademy.com/diagnosing-pistol-malfunctions-part-i-failure-to-feed/

[superdude]

AFTEC or standard extractor? Could excess extractor tension be slowing the round sliding up the breach face and then the slide gets too far forward on the round before it's high enough on the breach face?

The extractor is not involved in nosedive jams because the rear of the case has not started to slide up the breach face yet. That doens't happen until the nose of the round starts to enter the chamber.

I wouldn't be too quick to discount the extractor. Most everything I've read indicates that the case rim is entering the extractor groove at an angle as the round contacts the ramp, not when it's already entering the chamber. Here's one discussion:

http://aegisacademy.com/diagnosing-pistol-malfunctions-part-i-failure-to-feed/

When the nose of the round hits the feed ramp, the rear of the case is usually still held by the magazine's feed lips. That means it has not yet started sliding up the breach face.

It's absolutely the case when, as the OP has described, the nose of the round hits the inside of the magazine.

And I see that Howard Hall, or whoever put that page together at the link you posted, has stolen a figure from my website without asking permission, without giving me credit, and without paying me and has posted it on that page. How nice.

[tyler2you]

When the nose of the round hits the feed ramp, the rear of the case is usually still held by the magazine's feed lips. That means it has not yet started sliding up the breach face.

It's absolutely the case when, as the OP has described, the nose of the round hits the inside of the magazine.

And I see that Howard Hall, or whoever put that page together at the link you posted, has stolen a figure from my website without asking permission, without giving me credit, and without paying me and has posted it on that page. How nice.

Sounds like you need to send Mr. Hall a nice note

Could it be then that the feed lips are opened too wide and aren't controlling the round properly. I've read about the controlled feed principles of the 1911 platform and the theoretical "3 points of contact" that lead to reliable feeding. Not sure all of this directly translates to the 2011 with a ramped barrel, but here's a rundown on the 3 points of contact principle:

http://forum.m1911.org/showthread.php?9178-Controlled-Feed-Principles

[Sarge]

Nice debate guys! If you read my posts at all you know I don't give two $#|t$ wether we strongly debate things or not but just do me a favor this once and don't give the mods reason to close another of my threads!

But I am learning and taking notes on every sentence. Something that caught my eye was that maybe they are sitting too high in the mag. Rear dimensions on my mags are averaging .362 and front is .368. Possible if I have an imperfection on this slide that the 2nd round in the mag is sitting up just enough to snag?

[digi531]

This problem is interesting because ( IT ONLY HAPPENS DURING A MATCH ) Something YOU are doing during the match is the key here. Sorry, I don't know what that is, however, my experience with a MATCH feeding issue is usually my thumb making slide contact and inducing the feeding jam. If the mags work in one gun then they work, I use the same mags ( STI) in several of my open guns without issues. You must try to recreate match shooting and reevaluate.

[teros135]

Just FYI, my Open gun doesn't like wide feed lips for either 9 or 38. My MBXs came at about .342 rear .348 front, and these dimensions work for my STI mags as well (will be selling these, like the MBX). Wider, they jam. This is true for several friends' guns also.

[sauza45]

When you practice are you loading the mags the same way as a match as in same number of rounds. Does it happen at a certian number of rounds in a mag? Also have you replace the grip, ie plastic with plastic.

If so maybe the new grip is slighty different in the mag release area.

[CHA-LEE]

Focus on the function of the mags. Load up your mag to full capacity then thumb the rounds out one at a time. There should NOT be any tendency to nose dive as you thumb the rounds out. If there is then you have a brass issue that is allowing the rims of the brass to catch on one another before the round has left the feed lips. If the rims catch on one another it will nose dive. Another thing to look for is how aggressively the rounds snap up to the top position as you flick the top round out. Every time you flick the top round out the next round should snap up to the top position aggressively.

If you think there is a potential "Rim on Rim" catching issue or "Slow registration" issue you can verify that by spraying the inside of the mag tube with silicon or teflon dry lube to see if the issue subsides. Spray the ammo as well then repeat the thumbing the rounds out test to see how it functions with everything lubed up. If there is a dramatic reduction in rim on rim catching or increased registration speed then you are dealing with a brass issue or friction issue within the tube.

When I shoot open I use Liquid Wrench Dry Lube to spray the inside of the tube, follower and the ammo to ensure proper feeding. It can run without it, but I like the extra insurance.

[superdude]

It's not rim catching rim, it's the upper round's rim in the underlying round's extractor groove. This happen when the rim is wider than the case head, which it tends to be for many cartridges. In order for the rims to catch, the upper round would have to be positioned farther back in the magazine than the underlying round, which is damn near impossible.

If there is a gap between the front of the top round and the underlying round, typical in single stack mags, variable for double stack magazines depending on design, the rim will be in the extractor groove of the underlying round, and it will encourage nosedive.

Nosedive in single stack mags is explained in detail at the link below. Read it soon because that page will be removed very soon.

http://38super.net/Pages/Nosedive.html

[GrumpyOne]

It's not rim catching rim, it's the upper round's rim in the underlying round's extractor groove. This happen when the rim is wider than the case head, which it tends to be for many cartridges. In order for the rims to catch, the upper round would have to be positioned farther back in the magazine than the underlying round, which is damn near impossible.

If there is a gap between the front of the top round and the underlying round, typical in single stack mags, variable for double stack magazines depending on design, the rim will be in the extractor groove of the underlying round, and it will encourage nosedive.

Nosedive in single stack mags is explained in detail at the link below. Read it soon because that page will be removed very soon.

http://38super.net/Pages/Nosedive.html

Why will it be removed?

[Sarge]

Focus on the function of the mags. Load up your mag to full capacity then thumb the rounds out one at a time. There should NOT be any tendency to nose dive as you thumb the rounds out. If there is then you have a brass issue that is allowing the rims of the brass to catch on one another before the round has left the feed lips. If the rims catch on one another it will nose dive. Another thing to look for is how aggressively the rounds snap up to the top position as you flick the top round out. Every time you flick the top round out the next round should snap up to the top position aggressively.

If you think there is a potential "Rim on Rim" catching issue or "Slow registration" issue you can verify that by spraying the inside of the mag tube with silicon or teflon dry lube to see if the issue subsides. Spray the ammo as well then repeat the thumbing the rounds out test to see how it functions with everything lubed up. If there is a dramatic reduction in rim on rim catching or increased registration speed then you are dealing with a brass issue or friction issue within the tube.

When I shoot open I use Liquid Wrench Dry Lube to spray the inside of the tube, follower and the ammo to ensure proper feeding. It can run without it, but I like the extra insurance.

This takes me back to what I thought was the far fetched idea that wet tumbling was causing it. The brass feels leeched dry if that makes sense. Definitely doesn't feel as slick as when cleaned by dry method.

[superdude]

It's not rim catching rim, it's the upper round's rim in the underlying round's extractor groove. This happen when the rim is wider than the case head, which it tends to be for many cartridges. In order for the rims to catch, the upper round would have to be positioned farther back in the magazine than the underlying round, which is damn near impossible.

If there is a gap between the front of the top round and the underlying round, typical in single stack mags, variable for double stack magazines depending on design, the rim will be in the extractor groove of the underlying round, and it will encourage nosedive.

Nosedive in single stack mags is explained in detail at the link below. Read it soon because that page will be removed very soon.

http://38super.net/Pages/Nosedive.html

Why will it be removed?

An abbreviated version is going to be published, and it will be removed in compliance with the publisher's request. It's not unusual since publishers often buy the copyright for whatever they publish.

[theWacoKid]

Sarge,

Are you loading with no lube after wet tumbling? Maybe load with one-shot and leave it on the cases. That's what I do.

[Sarge]

Sarge,

Are you loading with no lube after wet tumbling? Maybe load with one-shot and leave it on the cases. That's what I do.

Yeah I lube.

[Sarge]

I almost wish both guns jammed! lol

Just can't grasp one gun being perfect and one having problems with the same ammo and mags.

[CHA-LEE]

Sarge> No two guns are identical. One may simply be a little more finicky than the other. For example, if the feed ramp depth is different between the two guns it can dramatically change how good/bad a certain length of ammo feeds in it. A good test that I do to see if my ammo OAL is set properly for the feed ramp depth is to black out the feed ramp with a sharpie marker. Then shoot 10 - 15 rounds and see where the sharpy marker is scuffed off of the feed ramp. If its hitting in the middle or just above the middle then the OAL is right where it should be. If its being scuffed below the mid point then the ammo is too short. Do this test with both of your guns using the same ammo to see if the scuff marks are happening at the same height on the feed ramp.

[dons]

On ‎8‎/‎9‎/‎2016 at 0:46 PM, zzt said:

The slide was actually outrunning the mag's ability to push a round up in time, because it sat lower in the mag to start. Have you replaced the recoil spring lately? If it was a little heavier than the last one, the slide may be short stroking a tad. That may cause the slide to move forward before the next round is high enough for proper stripping.

I've found this occurred in a number of limited and open guns, the recoil spring moves the slide forward faster than the magazine spring can properly feed a round up into loading position. this was my first thought when I saw this thread, even though you said you only run an 8 pound spring, which should be fine. However, I have a spring tester and found that sometimes springs are different than marked from the factory. I've fixed it by doing one of two things: Replacing the magazine springs (which you have already done), and putting a lighter recoil spring in (7 lbs).

Considering that this only occurs in one pistol and the magazines work in others, the only other thing that occurs to me is maybe the magazine release has worn or moved. You might check that.

Good luck and let us know if you come up with a solution.  Must be very frustrating for you.