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9/22/2017 12:11:25 AM
Posted: 8/28/2005 11:47:33 AM EDT

Howdy, folks.
I figure this one has a really simple answer, but I'd appreciate your advice. My ParaOrd P-13's slide is locking back with one round left in the mag on probably two out of every three mags I put through it. The mag springs were way underpowered, so I replaced with Wolff springs. Feeds much better, but now locks on the last round. What say ye?

Thanks in advance.
Link Posted: 8/28/2005 11:58:59 AM EDT
Move your thumb???

Look at how the magazine follower engages the slide lock. It is not possible for it to engage the lock while ammo is still in the magazine. What is possible then?

Your thumb is all that is left…

Now having said that, notice there is a little round nose pin that engages the back of the slide lock. Also engages the safety.

There should be a small detent in the slide lock that the pin slips into. If missing or very shallow, the lock can engage under recoil especially if there is a little thumb pressure against it.
Link Posted: 8/28/2005 12:51:37 PM EDT

It's not my thumb. I've shot this handgun quite a bit and never had this problem. It only started after the new springs, and I carefully checked to ensure that my grip didn't allow me to accidentally engage the slide lock.

The noses of the detents are visible at the slide stop and safety ends.

This has only been a problem on the last round in the mag, and on two different mags that I tried, both of which have never exhibited this problem before.
Link Posted: 8/28/2005 1:26:02 PM EDT
Parrot32, I'm no authority on 1911s, and I mean no disrespect, but I'm going to throw my $0.02 worth in. First, the dished out area for the slide lock detent to fit into is rarely on any slide stop currently made. It does not have to be there, and lack of it will not cause the slide stop to ride up under recoil. A shooter's thumb can contribute to this, but it sounds like red_on_black has eliminated this.

red_on_black, I would suggest you take it to a smith. Or, if you have other 1911s, try it with a different slide stop. Though this would be rare, sometimes a gun can have a slide stop with an oversized intercept stud. The bevel at the bottom of the stud would have to be stoned slightly to remmedy this, if this were the case. A quick way to tell is to take a look the next time you get premature slide lock. See if the slide lock is only partially up into the notch in the slide. Also, see if the nose of the bullet is actually contacting the bottom of the slide stop.

It's hard to diagnose a gun over the internet, which is why I'm saying take it to a smith. However, here's a possible scenario. The slide stop you have has a stud that is a little too low. With a full power mag spring, consider this. The slide stop is under tension from the recoil spring and barrel link pushing it back into the lower barrel lugs. This causes friction. In a properly functioning gun, the mag follower pushes the slide lock up after the last round is ejected. With a weak spring, sometimes you will get a slide lock that does not fully engage, or does not engae at all. With full power mag springs, the follower is pushed up properly.

What I think is happening with your gun is that with the full power springs, the last round is pushing up the slide stop just barely. It wonly manifests on the last round because with another round underneath it, the top round stays back because of greater spring pressure and the friction of to metaillic cartridges against eash other. On the last round, you have a plastic follower with less tension pushing up on the last cartridge, and when the second to last round is fed, the last round jumps forward just a little when the gun cycles into battery. Now you have a round slightly forward that bumps the slide top up on recoil. It's just a theory, and I would have to see the gun in order to cinfirm it.

Anyway, good luck. Let us know how it turns out.
Link Posted: 8/28/2005 1:47:45 PM EDT

That sounds like a pretty reasonable scenario. When it locks prematurely, the slide stop is only engaging maybe a third of the notch. Furthermore, sometimes when it feeds all the rounds before locking the last round loaded clearly cycles MUCH slower than the previous rounds, which sounds a little like it fractionally engages the notch but isn't able to lock the slide back.

Thanks for the input guys-- I'll see what I can do with it.
Link Posted: 8/28/2005 2:56:30 PM EDT
The diameter of the slide stop should be a uniform 0.200 inches from end to end. If you have access to a micrometer that might help your diagnosis.
Link Posted: 8/28/2005 6:48:18 PM EDT
[Last Edit: 8/28/2005 7:48:04 PM EDT by Dano523]

Originally Posted By red_on_black:
My ParaOrd P-13's slide is locking back with one round left in the mag on probably two out of every three mags I put through it.

The mag springs were way underpowered, so I replaced with Wolff springs. .

Easy fix, you need to pull the spring back out of the mag, and bend the "just past the top coil as it clears theonce around the follow and starts to make the drop at the straight section" down to slightly cant the front of the mag follower more downward wehn its in the mag. Currently with the mag wolff spring installed, there is too much force on the front of the follower, and the when the slide hit the back of the frame of cycle, the front of the follower has just enought front force to lift the catch (the front force on the follower is greater than the rim force and the round gets danced (back off the feed lips) in the mag).

I run into this same problem every time I change out the Wolf springs to new units on the mags for my Practice USPSA rig (16-40 limited).
Link Posted: 8/28/2005 10:18:22 PM EDT
Try bending the mag feed lips inward (towards each other) just a little bit. I had this problem with a different kind of handgun and I gently bend the feed lips inward and the problem stopped.
Link Posted: 8/29/2005 4:19:03 AM EDT
red_on_black: I hope you didn't find my "Thumb" suggestion condescending. That was not the intent!

hobbs: How could anyone take offense to your well thought out reply???

I went back and looked at my Colts. All have a dimple on the slide lock for the pin to engage. Of course my 'newest' is 15 years old…

I had premature lock engagement problems with my 10mm. Increasing the dimple eliminated that. However I will keep in mind the good information presented here, much of which I had never thought of!

I hope red will keep us informed of his findings.
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