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  #26  
Old 02-18-2020, 08:50 PM
jtq jtq is online now
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Quote:
Originally Posted by Pony doc View Post
Would it be appropriate to try a GI style feedlip since I only shoot round nose bullets?
Sure
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Originally Posted by jtq View Post
You can use them, they feed smoothly, but they are not common.
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  #27  
Old 02-19-2020, 08:27 PM
Pony doc Pony doc is offline
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Quote:
Originally Posted by Steve in Allentown View Post
That's a tricky question. I'm sure there are specs somewhere for the width across the lips at the front of the magazine but they are probably for GI fully tapered lips.

I would measure all the magazines at the same spot then compare these measurements for each mag to see if they are all the same or how much variance there is between them.

I found this doing a quick search. I suspect you'll find lots of info by doing your own search.
I tried measuring feed lips but it was pretty much a bust. It was difficult to measure the back of the feedlip with enough consistency to make meaningful comparisons. It was difficult to keep the calipers square at the back of the feedlip so my calipers would be canted ever so slightly across the back of the feed lips making my measurements unrepeatable. The only spot I could reliably measure was the bottom of the little notch below the back of the feedlip but that is not a measure that means anything.
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  #28  
Old 02-19-2020, 10:35 PM
BBBBill BBBBill is offline
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Quote:
Originally Posted by Pony doc View Post
…It was difficult to measure the back of the feedlip with enough consistency to make meaningful comparisons. It was difficult to keep the calipers square at the back of the feedlip so my calipers would be canted ever so slightly across the back of the feed lips making my measurements unrepeatable…
Were you trying to hold the mag in one hand while measuring with the other? Work on your technique. Gently clamp the mag tube in a soft vise just tight enough to hold it steady, freeing both hands to work with the calipers. Clamp right at the bottom so the pressure is directed through the base plate to avoid compressing/denting the mag tube. Hold you calipers with both hands so that you can control the position of the jaws on the feed lips.
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  #29  
Old 02-22-2020, 05:34 PM
Pony doc Pony doc is offline
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Been busy investigating. Measured the feedlips on 13 mags. Measurements are in the photo attached. The star next to mag 13 means it has been my most troublesome mag. The two with dots indicate that they have malfunctioned at least once. Measurements don't seem to indicate to me a feedlip spreading problem. After reading some of 1911 Tuner's articles on feeding I decided to do do a little measuring. With the pistol disassembled, it does not appear that I have at least 1/32" clearance between the feedramp and the barrel ramp. Photo was taken with the barrel lugs touching the VIS. Tuner seemed to think this measurement was critical and so did Mr. Kuhnhausen. Not sure if any thing can be done for it and it still does not explain why only a few mags ever malfunction.

Also, I removed the firing pin and recoil spring and hand cycled rounds through the gun. I could induce the identical malfunction contained in my first post with magazine 13 on the 5 th round. However, I could also get the same malfunction with magazines that have never malfunctioned in any of my pistols. Not sure how reliable this test is. I also shot 3 full magazines through another 1911 with no malfunctions. Checked extractor tension while I was at it and tension seemed fine to me via the shake test. Beginning to believe it is something wrong with the pistol and not the magazines. I failed to mention this in any of my earlier posts that these mags run fine in another series 70 Colt and a 1991A1 Commander that ran several thousand rounds without a hiccup. What now?
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  #30  
Old 02-22-2020, 06:21 PM
Steve in Allentown Steve in Allentown is offline
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Quote:
Originally Posted by Pony doc View Post
Measurements don't seem to indicate to me a feedlip spreading problem.
Where along the length of the feed lips did you take the measurement? At the rear, at the front?

Your measurements look too wide to have come from someplace along the lips. Might you have taken your measurements from in front of the lips?

The feed lips are supposed to release the cartridge at a specified distance from the rear of the tube. Unfortunately, I don't remember what that distance is according to ordnance specs and each mag manufacturer uses their own unpublished specs.

Quote:
. . . it does not appear that I have at least 1/32" clearance between the feedramp and the barrel ramp.
You can see how Colt deals with this by cutting a "dimple" in the barrel's clearance ramp. Being very careful you could move the clearance ramp ever so slightly forward but this is not for the faint of heart.

Here's how the pros do it: https://forums.1911forum.com/showpos...69&postcount=9


However, the lack of the 1/32" gap is not what is causing your intertia feeds.

Nor is the extractor causing these inertia feeds.


.

Last edited by Steve in Allentown; 02-22-2020 at 06:45 PM.
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  #31  
Old 02-22-2020, 06:48 PM
Pony doc Pony doc is offline
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Measurements ware made at the back of the feedlips o.d. measurement. Maybe that is not right?
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  #32  
Old 02-22-2020, 07:09 PM
Steve in Allentown Steve in Allentown is offline
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Quote:
Originally Posted by Pony doc View Post
Measurements ware made at the back of the feedlips o.d. measurement. Maybe that is not right?
You have to measure the inside distance.

What's important to know is how soon the feed lips are releasing the cartridge. If the lips are spread too wide, too soon, the cartridge may jump out of the magazine as the cartridge scoots forward in the magazine due to the effect of inertia.

The feed lips on a GI full tapered feed lip magazine are quite long and don't release the cartridge until it is quite far forward. Therefore, a little scooting forward of the cartridge in the mag doesn't result in an inertia feed malfunction.

The feed lips on a wadcutter parallel feed lip magazine are quite short and release the cartridge early in the cycle. The reason these mags aren't as prone to inertia feeds is that the feed lips don't spread apart at any point and so don't allow the cartridge to scoot forward as much as tapered feed lips.

Hybrid feed lips, as the name suggests, split the difference between the first two mags. The lips are longer than the wadcutter but shorter than the tapered. Also the lips spread apart as the cartridge moves forward and release the cartridge before the tapered lips but after the wadcutter.

Understand that when I say the lips spread apart I don't mean they are being pushed apart. Rather, the designed distance between the lips increases as you move from the rear toward the front. This allows the cartridge to rise up the breechface as it moves forward which presents the nose of the bullet higher in relation to the frame feed ramp.

The only other advice I can think of right now is to make sure the interior of the mags and the followers are bone dry. You don't want any oil anywhere near the underside of the feed lips. You don't want to make it easier for the cartridges to scoot forward on their own.

.

Last edited by Steve in Allentown; 02-22-2020 at 10:10 PM.
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  #33  
Old 02-22-2020, 08:35 PM
megafiddle megafiddle is offline
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Something you might try:

Remove the slides from the frames of the gun that jams and a gun that works.

Load the most troublesome magazine and place it in one of the frames.

Slide the rounds forward and out one by one, noting whether they move freely, or stop on the frame ramp. Then try the same with the other frame.

This may disclose some difference in the location or angle of the frame ramps in relation to the magazine top.

There will be some variations in the angles of various rounds as they leave the magazine. So you will be looking for some overall trend between the two frames.

Also, is there any difference between the bottoms of the firing pin stops of the guns that work and the gun that doesn't?

-

Last edited by megafiddle; 02-22-2020 at 08:50 PM.
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  #34  
Old 02-23-2020, 10:30 AM
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RickB RickB is online now
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Quote:
Originally Posted by Pony doc View Post
Measurements ware made at the back of the feedlips o.d. measurement. Maybe that is not right?
I'd try to measure at the release point. At the rear, I'd expect all mags to be about the same, regardless of feedlip style.
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  #35  
Old 02-23-2020, 11:47 AM
Pony doc Pony doc is offline
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Quote:
Originally Posted by megafiddle View Post
Something you might try:

Remove the slides from the frames of the gun that jams and a gun that works.

Load the most troublesome magazine and place it in one of the frames.

Slide the rounds forward and out one by one, noting whether they move freely, or stop on the frame ramp. Then try the same with the other frame.

This may disclose some difference in the location or angle of the frame ramps in relation to the magazine top.

There will be some variations in the angles of various rounds as they leave the magazine. So you will be looking for some overall trend between the two frames.

Also, is there any difference between the bottoms of the firing pin stops of the guns that work and the gun that doesn't?

-
Disassembled both pistols and taped the barrels in place. Used my thumb to push several mags worth of cartridges from both the troublesome mag and one that has never malfunctioned through each pistol. Cartridges would impact the feed ramp near the very top of the ramp and slide over the lower surface of of the barrel ramp. When the case rim reached the release point the case snapped up to where it was entering the chamber perfectly in line with the bore. If there was a difference between the guns or magazines I was not able to detect it.

I can't discern any difference in the FPS between the two pistols. Both are factory Colt

Will try to measure the I.d. of the feedlips at the release point
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  #36  
Old 02-25-2020, 06:15 PM
Pony doc Pony doc is offline
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Originally Posted by RickB View Post
I'd try to measure at the release point. At the rear, I'd expect all mags to be about the same, regardless of feedlip style.
Ok. At long last I have measurements of the I.d. width of the feedlips at the release point. The star indicates the troublesome mag. Dots indicates mags that have demonstrated the missfeed demonstrated in the original post. Actually a fairly wide variability but the troublesome mag appears to be midrange. Mags 8,9, and 10 are narrower but they are also the newest Ed Brown mags and 1 year old compared to the others which are 7-12 years old. A hammer is beginning to look like a distinct possibility or just never pair it with this pistol since it seems to work fine in my others.
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  #37  
Old 02-25-2020, 07:54 PM
Steve in Allentown Steve in Allentown is offline
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I know this is aggravating and frustrating but there's one more dimension that may uncover the secret of this malfunction. Can you get a measurement from the rear of the magazine tube to the release point for each mag and pair that up with the width of the release point for each magazine?

So, you'd end up with two measurements for each mag:
  1. Width of the lips at the release point
  2. Distance from the rear of the mag to the release point
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  #38  
Old 03-02-2020, 07:04 PM
Pony doc Pony doc is offline
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Ok. Finally had time to measure. This is from the back edge of the magazine to the beginning of the release point. Nothing really stands out to me looking at the measurements. Mag 13 is the least reliable. 9 and 10 occasionally provide the same missfeed in one 1911. All mags work fine in the other 1911. As always, open for suggestions.
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