Gunsmithing 1911 slide failure to lock open on an empty magazine - new cause

[Steve in Allentown PA]

This subject has been addressed many times and solutions include such things as replacing the magazine spring, bending the engagement tab on the follower outward, replacing the slide stop, using hotter ammo, replacing the recoil spring with a lighter one, and others.

Today I discovered a new-to-me reason for this kind of malfunction.

I had multiple failures-to-lock-open with three specific magazines. I chalked it up to cold weather and/or a weak powder charge. But this just didn't make sense to me since this pistol has had thousands of rounds through it with many magazine brands and has always run 100%.

When I got home I disassembled the three problem mags and remembered this was their first trip to the range. I put the followers back in and did my usual teeter totter test which they all passed. Then I put the mag springs back in with just enough tension to provide some resistance to the follower. I pushed each follower down and slowly let the springs push them back up and each follower got stuck just before coming all the way up into contact with the feedlips.

After a few more diagnosics I determined there was a burr left over from the manufacturing process on the inside surface of each mag tube in just the right place to prevent the follower from coming into contact with the slide stop lobe. This did not affect the feeding of the last round in the mags.

The fix was removing the burrs. Another trip to the range and the mags ran faultlessly.

The arrows in the pictures below point to the spot where the burrs occurred (inside the mag body).

Here's some more detail to show where the burr occurred and how it interacted with the follower.

"A" and "B" in the picture below are pointing at different areas of the tab on the mag follower that makes contact with the slide stop lobe to push it up after the last round in the magazine is sent down range.

"A" indicates the very top surface of that tab. This is what actually contacts the underside of the slide stop lobe. If you look very carefully, you can see this surface looks a little different than the rest of the follower. That's because the follower wasn't cleaned after shooting and the powder residue has been worn away in that spot because of repeated contact with the slide stop lobe. This picture was taken after I'd gotten rid of the burr and the follower was now doing its job of holding the slide open.

"B" indicates the very edge of the tab where it had been running into the burr. Once again, a close examination will reveal a very small area where the bluing had been worn away by the burr.

"C" in the picture below shows the exact spot where the burr and the follower met. When this happened the follower would stick which meant the follower tab couldn't push the slide stop up to engage the slide. Note how the follower is not fully up against the feedlips.

The follower had not been stopped by the burr until after the last round had been chambered. At that time the follower rose up in the tube but was still being slightly depressed by the disconnector rail. When the slide moved rearward and the disconnector rail was no longer depressing the follower, the follower moved up enough to hit the burr which stopped it in the position shown in the picture.

 

[Sam Dunham]

"Disconnector rail", you mean, Pick up rail?

 

[Steve in Allentown PA]

It's known by a number of names. I don't know off the top of my head if the ordnace blue prints actually assign it a name. I call it the disconnector rail because the disconnector contacts it. Without it the disconnector wouldn't be able do its job. Whatever you or I call it I think we both know what the other is talking about. I'd be interested to know if there's an official name for it.

 

[DaleGribble82]

Who was the manufacturer of these three problem magazines?

 

[Steve in Allentown PA]

Who was the manufacturer of these three problem magazines?

The mags were sold by Ed Brown for $10 each as part of a magazine exchange promotion that may still be ongoing. I hasten to point out that of the twenty or so mags that I received only six had burrs. Conversations with others who also took advantage of the mag exchange revealed that they did not find any mags with burrs. So, I think I must have been the lucky one who got all of the ones that slipped through the QC function.

The original manufacturer of the mags was Checkmate. I have another two dozen or so of these mags that I've bought over the past few years mainly from Top Gun Supply, None of them have any burrs. The mags are 8 round, extended tube, hybrid feed lip, with a Checkmate follower (CM45-8-S-RB-EXT ). These are hands-down my favorite mags because of how smoothly they feed.

A year ago I spent 3 straight days testing every size 1911 I had on hand with every brand of magazine and factory FMJ & JHP ammo as well as my handloads. I had a wide variety of magazines from Checkmate, Wilson, CMC, Tripp, MecGar, and others. I ran through literally thousands of rounds and my thumb hurt long after the testing was finished. The results were convincing - the Checkmate mags fed the smoothest across all ammo and all pistols.

 

[DaleGribble82]

Nice, thanks for the info. I’m currently in the same process testing out different mags for my Les Baer TRS. I’ve ran Baer, various Wilsons and various CMC, and Colt mags. I’ve yet to try out any checkmates though. Sounds like that’ll be next on the agenda.

 

[Sam Dunham]

It's known by a number of names. I don't know off the top of my head if the ordnace blue prints actually assign it a name. I call it the disconnector rail because the disconnector contacts it. Without it the disconnector wouldn't be able do its job. Whatever you or I call it I think we both know what the other is talking about. I'd be interested to know if there's an official name for it.

It picks up the Cartridge and pushes it forward.

 

[Steve in Allentown PA]

It picks up the Cartridge and pushes it forward.

Yes it does. It also interacts with the disconnector and the hammer. It also holds down the next round in the magazine.

 

[Steve in Allentown PA]

Thanks for the info Steve. I am a big fan of the 1911 & am always searching for new answers to common shooting problems.

Thanks for the thanks. After 46 years of carrying, shooting, and fixing 1911s I've managed to learn a few simple things to keep these beasts running. Whatever I know I learned from others and am just glad to be able share whatever I know. You may find this link to be of some passing interest: 1911 Extractors

 

[Sam Dunham]

OK, Bro, it can be whatever you call it.

I am not challenging your knowledge base nor am I tooting my horn when I say that the "pick up rail" is what every pistol smith at the two places I worked and built them used when referring to it. I respect your 46 years of 1911 experience. I carried a 1911 every day for 17 years in LE and up until they drug me to the Glock pistol as an issue item. I came to also respect the "Gaston Gun" and carried it daily for the last 12 years of my tour. I have no claim to fame but I did spend years fitting slides and frames and barrels along with extractors by the thousands 40 hours a week and sometimes on Saturdays so I am not without some knowledge of the 1911 and its various clones. One of the things with the Beast is the extractor and yes, it requires some expertise to make the pistol run 100%. The good thing about working and learning in a major build shop and Manufacturer of Top quality pistols is the sheer volume you shoot and handle. Test fire for at least 6 months before you get on the build bench no matter what you know. The requirement and quote, "All ours smiths have to be able to shoot first" was not even phased by stating "I am NRA Distinguished PPC and Combat Master. You still have to get in the line and as you do, you shoot thousands of pistols ( over time) and thousands of rounds a week. I am very particular to the original Wilson 7 rounder for 45's and to this day still, use them with replaced followers but have never had a soft spring or malfunction due to my magazines. I am still learning also and if I was not, would be stagnant. There are those still who may have forgotten more than I know yes. Good to be here and good to enjoy your subject perspective on a nomenclature that I have never heard of and would also be interested in the so-called "Correct" Nomenclature. Very good link on extractors!

 

[Steve in Allentown PA]

Sam, your experience speaks volumes. Hell, I don't know what to call that thing. Some refer to it as a lug but we all know what it does.

Wilson makes good magazines. I had a strong preference for McCormick mags for years when I shot IDPA. Everyone seems to have their favorite brand. The good news is that if a 1911 is put together correctly, there will be few magazines that won't run in it.

Thanks for the thanks. I put that together as an attempt to consolidate the things I learned about extractors over the years in a single location and in such a way that anyone could understand it.

I look forward to tapping into your many years of experience. If I ask a dumb question from time to time, be kind.

 

[Sam Dunham]

You have extractor down, way down and good to go! The very best extractors I have seen were Cryo treated but the Marine Corp seemed to break even them. Your excellent input on "Crashing" into the case and proper deflection, poundage of pressure and the proper "Hook" adjustment are what I think happened to many they were sent. From the few I saw returned, instead of proper hook/extractor "Claw" looked like they were just bumping the front of the hook on a belt sander to avoid crashing and in the process weakened the extractor to the point that a hung case extraction would simply break it off.

 

[Steve in Allentown PA]

Marines. No finesse at all.

At first many folks don't realize that a 1911 is just a small machine and the parts that go into it don't require a wood rasp to fit.

 

[DaleGribble82]

My 1911 is by far my favorite firearm. It’s a piece I will never part with. Accurate, reliable, and timeless. Truly a work of art.

 

[Jefe's Dope]

Checkmates have served me well.

 

[Sam Dunham]

While I was in test fire I shot a lot of varieties of 1911. I have had old rattle traps that would shoot 5 touching at 15 yards off the bags. The one thing these old guns that shoot well have in common? Pretty consistent lock up with none to very little barrel pushdown. Some barrels with shallow grooves would not shoot the H&GVit load very well but would shoot ball very much better. The ball had the harder surface area to stabilize in the shallow grooves and let the lands work. I am sure people shoot the old Civilians and Military guns with lead and say they are not shooters, "The barrel is worn out" and other things that are just not true. They were designed for ball ammo and that is what they shoot well. Course the Storm Lake and other makers are cutting the lands and grooves to shoot lead well now. I must admit my preference for Wilson Mags mainly because that is all I used aside from the old Colts and some of the early Pachmyr mags. 1911 with just a little tune added is a reliable sidearm and can be depended on but is not deserving of the rep some give it saying it is hard to master. just not true. It takes competence to learn any system. Just to illustrate ignorance, I had a District Court Judge tell me to go outside the Courtroom and "UN-Cock my pistol!" Total Dipstick!