75B 9mm Slide Doesn't Lock Back

[1SOW]

Pistol: 9mm 75B, 11# (minus two coils) recoil spring, 13# (minus two coils) hammer spring, 50K+/- rds.

I use 6 mags, 4 Mec-Gar and two stock all 16 rds. Last spring replacements were about 6-7K rds ago. Followers were replaced about 10-15K back.

Never had a mag problem of any kind.

First I had one Mec-Gar mag that didn't lock back after the last rd. Now, two weeks later, another one (didn't catch which type it was) won't lock back.

Where would you start?

I appreciate your help.

[CeeZer]

Start with replacing mag springs.

[Lunker]

If mag springs don't do it, try new #11 recoil spring.

[schmeky]

1SOW,

I know you know this, but check the actual notch in the slide rail. This notch can slowly round off over time. Here is a pic of a new CZ that would not lock the slide back. I had to recut the slide notch.

[ck1]

Maybe worn out slide-stop spring or possibly the slide-stop's notch has rounded off..?

[1SOW]

1SOW,

I know you know this, but check the actual notch in the slide rail. This notch can slowly round off over time. Here is a pic of a new CZ that would not lock the slide back. I had to recut the slide notch.

THANKS schmeky, I did forget about that possiblity--duh. Just checked it. It still looks square and uniform. It is very polished about the last 1/64" from the edge. It "could" be worn back a .0001", but nothing really visible to the/my naked eye. Should I hand work it to a sharp fresh "face"?

One mag made me think mag-spring. A second mag less than 2 weeks later, and I begin to doubt they both started failing at the same time, but maybe so. I do try to rotate their use evenly.

ck1:

Maybe worn out slide-stop spring or possibly the slide-stop's notch has rounded off

..?

I did check that. The slide stop was replaced quite a while back, and it still looks good with a sharp edge bjust slightly polished. Thanks, good thought.

Any more ideas before I visit Wolff's gunsprings.com for 6 +10% magsprings and a recoil spring??? Come to think of it, I may try the 11# Browning HP recoil spring that is said to actually fit the 75B plastic guide rod a little better.

Edited December 23, 2011 by 1SOW

[CeeZer]

Maybe worn out slide-stop spring or possibly the slide-stop's notch has rounded off..?

Those would cause premature slide locking.

[1SOW]

Maybe worn out slide-stop spring or possibly the slide-stop's notch has rounded off..?

Those would cause premature slide locking.

If the notch is rounded it will slide right over the slide stop.

I'm not experienced with the spring. My four other mags still lock back. When I shoot steel, I use my son's two 19 rd Shadow mags and they still lock back too.

Edited December 24, 2011 by 1SOW