Ruger P 89 question

[osteodoc08]

I've got a Ruger P89 that I've put over 3500 rounds through. Lately though the slide will not stay back when I put a full magazine in, it will go forward. It is rather disconcerning. Ruger seems to think it is the slide stop and is sending me a new one. I am under the impression that it is a weak spring.

The slide will stay put if I put the new mag in gently, however, I normally just slap it home with the heel of my palm. It will only do it with a full mag, not with just 1-2 in it. It is like there isn't enough spring tension on the slide stop and when I slam a full mag home and it causes the slide to move just enough to have the slide stop move down since the mag is full. Everything else is okay. Slide/frame fit is nice and tight.

I guess I will find out in a couple of days when my new slide stop is here.

 

[misANTHrope]

Well, the only "spring tension" that pushes the slide stop upward is provided by the mag's follower- when you discharge the last round, the follower pushes the stop upward as the slide cycles, the notch in the slide catches it on the way forward, and the slide locks open. Once you remove the magazine, the only thing holding the slide stop up, and by extension, keeping the slide locked back, is the interference fit between the slide and stop, where friction is kept high due to the recoil spring pushing the slide forward.

I would wager that the contact surface of the slide stop has worn down and the contact area has shrunken enough the a good smack, such as that administered while inserting a mag, is enough to jar the stop and release the slide.

As a caveat to this, I'm not a gunsmith, but rather a mechanical engineer, one who has stripped his P94 down to the bare frame once just for fun, so please keep a grain of salt handy.