Premature Slide lock

[firecracker6]

Quite some time ago, someone on this forum was having a problem with premature slide lock. I replied that I'd had the same issue and resolved it by installing a cylinder and slide slide stop. A month or so ago I experienced premature slide lock while shooting 230 grain gold dots with a Tripp Research mag. I loaded up 100 rounds of gold dot and fired them using different brands of magazines. I've used ACT, 2 types of mecgar, chip mccormick, wilson combat and a mystery mag with no issues. Tripp Research makes great magazines but for some reason my rock doesn't like them.

[Steve in Allentown]

Do you suppose it's possible that the follower or the magazine itself of the Tripp sits just a little bit higher in the magwell than the other mags and therefore engages the slide stop lug as the last round in the mag moves up against the mag feed lips?

Does the premature slide lock always occur with the last round in the mag still in the mag?

[firecracker6]

It seems to occur at random so I don't think it's the follower. I suspect that brand of mag sits up higher in the gun for some reason. I've used 4 or 5 different bullets and I've only had a problem with the gold dots for some reason. Since I know someone is going to ask, my support hand isn't the problem. As an aside, I've probably shot a couple of hundred of XTP's through it without issue. It seems counterintuitive to me but I'm starting to think the conical shape of the XTP's is more reliable (I'm using the old COL).

[Steve in Allentown]

Perhaps the recoil impulse of the Gold Dots is different enough from the other ammo that the plunger tube spring isn't able to keep the foward plunger pin in solid contact with the slide stop.

Maybe a new plunger tube spring will cure this: https://www.gunsprings.com/COLT/1911%20GOV'T%20PISTOL/cID1/mID1/dID1#818. For $3.50 it's not a big gamble to try.

Or maybe the forward plunger pin has compromised geometry and replacing it might cure the problem it and for $2.00 it's cheap to try: https://www.egwguns.com/plunger-tube-pin-slide-stop-ss

Another possible cure and the most difficult is cutting a shallow divot in the the slide stop where the forward plunger tube rests when the slide stop is in the full down position.

Lastly, have you carefully examined the slide stop lug for indications of bullet contact? If there is contact, carefully and minimally filing the contact point to prevent bullet contact could solve the problem.

[Jim Watson]

Another possible cure and the most difficult is cutting a shallow divot in the the slide stop where the forward plunger tube rests when the slide stop is in the full down position.

Lastly, have you carefully examined the slide stop lug for indications of bullet contact? If there is contact, carefully and minimally filing the contact point to prevent bullet contact could solve the problem.

A guy here had premature slide lock. He filed all he thought safe (I once took off too much and with a little wear, it was missing slide locks.) so then he had a friend with machine tools put a detent on the slide lock lever.

[Hawkmoon]

It seems to occur at random so I don't think it's the follower. I suspect that brand of mag sits up higher in the gun for some reason. I've used 4 or 5 different bullets and I've only had a problem with the gold dots for some reason. Since I know someone is going to ask, my support hand isn't the problem. As an aside, I've probably shot a couple of hundred of XTP's through it without issue. It seems counterintuitive to me but I'm starting to think the conical shape of the XTP's is more reliable (I'm using the old COL).

The Gold Dots may have a fatter ogive profile than the others. The Tripp follower may not be as aggressive as other followers in holding the last round back under recoil, and/or the feed lips may be more slippery, allowing the top round (or the entire stack) to move forward just a bit under recoil. If that happens, the "fat" part of the ogive can scrape the slide stop enough to engage the slide. Examine the inside of the slide stop lug for traces of copper. If you see copper, that's the problem. The solution is to carefully file a slight radius into the lug at the point where you see the copper deposits.

Slide Stop.jpg

[firecracker6]

I'd like to thank everyone for the input; I can tell you are all very competent people. I don't think it has anything to do with the recoil impulse as I've no trouble with any other brand of magazine. I know the original slide stop had copper all over it which is why I replaced it. I've not fired enough gold dots with the new slide stop as gold dots aren't cheap, even though I roll my own. I like the idea of putting a small divot in the slide stop; I might do it just for fun. I'm not sure if I'm going to rectify the issue or just avoid using Tripp Research mags in this gun. I've plenty of mags and guns to use them in. I've considered altering the slide stop so it won't lock the slide back at all. I'm kind of weighing the increase in reliability vs the likelihood of needing the slide lock back feature. If I had a job where I did lots of CQB or something it would probably be worth having the slide lock back on the last round but it might be different since I'm merely a CCW person. I'll probably alter the old slide stop so it won't lock back the slide and see how I like it.

[Hawkmoon]

Before altering the old slide stop so that it won't lock the slide at all, try altering it as shown in my sketch. You can test by installing the slide stop in the gun with the slide removed. Load a magazine with the Gold Dots, make sure the rounds are all tapped fully to the rear, and then just nudge the top round forward by about the equivalent of two thumbnail's thicknesses. Then hold the slide stop down gently while inserting the magazine, and watch for whether the bullet makes contact with the slide stop lug.

To do the alteration shown in my sketch, I use a curved-face (not round or half-round) jewelers file. If you don't have one, the set from Harbor Freight Tools will be adequate. For four bucks, you shouldn't be without them. https://www.harborfreight.com/12-pie...-set-4614.html

Don't take off too much at once. File a bit, test, and repeat as necessary.

As to the recoil impulse not being the culprit -- with the Tripp magazine, when you first load it and tap the spine to ensure that all rounds are fully to the rear, does the magazine load into the gun and the first round feed reliably? If so, then the recoil impulse clearly IS the culprit. You didn't say whether your Tripp magazine has the steel Flex follower or the polymer follower, but neither has the little "dimple" in the top surface. That dimple was specified by John Browning, and it has a purpose. The purpose is to prevent the rounds remaining in the magazine from nudging forward under recoil. As you shoot more rounds, the spring exerts progressively less pressure on the stack of rounds waiting to be fed. Without that dimple, it's not uncommon for there to be a point about halfway through the magazine when the spring pressure isn't sufficient for friction between the top round and the feed lips to hold everything back.

For rounds that have a "fat" ogive, with very little clearance between the bullet and the slide stop, it doesn't take much forward travel to result in interference.

[megafiddle]

...
You didn't say whether your Tripp magazine has the steel Flex follower or the polymer follower, but neither has the little "dimple" in the top surface. That dimple was specified by John Browning, and it has a purpose. The purpose is to prevent the rounds remaining in the magazine from nudging forward under recoil. As you shoot more rounds, the spring exerts progressively less pressure on the stack of rounds waiting to be fed. Without that dimple, it's not uncommon for there to be a point about halfway through the magazine when the spring pressure isn't sufficient for friction between the top round and the feed lips to hold everything back.
...

How can that dimple add any significant tension to the rounds, considering its small size?

-

[Steve in Allentown]

How can that dimple add any significant tension to the rounds, considering its small size?

It's purpose isn't so much to add upward pressure against the cartridge. Rather, it's purpose is to prevent the forward movement of the cartridge by catching the rim. It's sort of like a speed bump.