Slide not locking back on last round: STI Spartan

[mpthole]

I haven't posted anything here for a while because my guns have pretty much been running well. But now, something new came up.

This is a relatively new (<2k rounds) STI Spartan. I'm using Wilson 8 round mags that have many, many rounds on them, but I just installed brand new ISMI springs. The title says it all - the slide will not lock back on an empty mag. It doesn't just happen with the Wilsons either... I've tried both 7 round Metalform and hi-standard mags. All of these mags function just fine in my other 3 1911s: 2 Springfields and one cobbled-together RIA.

I'm shooting the USPSA Area 5 match on Thursday, in the single stack division and would really like to get this gun running before then. Otherwise, it's back to shooting the RIA. Which is fine... I won my class at the last section and area match with it... but it would be nice to shoot the new one.

The only thing I can come up with is that the slide stop is not shaped correctly or has "worn" down or something. It worked fine for the first 1k rounds or so. Or maybe the recoil spring...? I've got a new recoil spring laying around I could throw in and try anyway. Don't know what to do if it's the slidestop...

 

[Jim Watson]

Take the slide off the receiver, then put the slide stop back in place. Insert a magazine and look to see where the magazine follower and slide stop lug line up. You may be in the market for a new slide stop, being that your magazines pick up the slide stops in other guns.

 

[mpthole]

Thanks, Jim. I will give it a look tomorrow evening after work.

 

[mpthole]

Click here for a picture (the scratch marks were my first file attempts)

It looks like there is a groove worn horizontally in the end of the slidestop, making for just enough resistance on the pin to keep it in the down position. The magazine follower is definitely engaging the slide stop... and oddly enough will push it up with the slide off the gun, but when the gun is together and I hand cycle some dummy rounds through it, it won't lock back.

I'm going to try filing a bit more and see if I can ease that dimple out.

 

[Jim Watson]

That is not a wear groove, it is an intentional detent to prevent premature slide lock engagement. Commonly recommended, easy to overdo. Maybe the detent could be opened out and softened a bit.

We were talking about another approach at
http://forums.1911forum.com/showthread.php?t=179508
see post #6.

You might have to buy a new slide stop and start over to form that faint bevel instead of a sharp hole.

Tuner probably knows a good approach, if he will chime in.

 

[CrazyIrishman]

Hey guys,

I had a similar problem when I first received my '57 Sistema Colt 45 acp a couple years ago. The original magazine looked to be ok as did the pistol.

After a through cleaning including the magazine, the problem of not staying locked open after the last round continued.

So, I bought an 8 round Mec-Gar magazine from Brownells ,a Wolfe mag spring, and a follower(forgot the brand). When I tried the new mag the problem went away. Right after that I replaced the old spring and follower with the new parts and wouldn't ya know, the problem was fixed!!

After closer inspection the culprit was mostly the spring being worn out, however, the follower showed wear too when compared to a new one. OTOH, without a new follower to use for comparison the older one didn't seem to be bad.

Bottom line... It was a cheap and Quick fix!!


I have "Tuner" to thank for the advice and suggestions that got the job done!!


Thanks Tuner!!


CI

Marty

 

[Trakker]

The opening on the slide stop may be too small.
A pillar file will open it up a little.