Hey all!
My first time posting in the Colt forum. I have a series 80 I purchased back around Christmas of last year that is exhibiting strange behaviour. While at a shoot in Virginia yesterday, I noticed that sometimes while inserting a new magazine and 'bumping it' with the heel of my hand to seat and lock it in place, my slide lock would sometimes release and go to battery without my touching the release lever. I inspected it and the only thing I can see that might be having any effect is the small transfer pin apparatus which appears to act as a detent of some kind. It isn't applying much if any pressure to the contact area at the rear of the lever. Is the lever supposed to be profiled any for the detent to work properly? Mine appears to have a smooth surface with no indentations. Is that the norm? I feel this might be a dangerous condition and should be remedied. I'd prefer not to have to send it to Colt if at all possible, but will if necessary. Any ideas? Thanks!
Big_Cheese

The slide stop should have a smooth face, so it's normal.  Also, the detent does not have that much spring pressure.  More than likely it's your mags, or you MIGHT have a tight fiitng slide stop where it contacts the link and bottom barrel lugs.  I kind of doubt that though.

Put an empty mag in the gun and pull the slide back.  When it catches, look to see if the lock of the slide stop goes all the way up, or just partially.  It's fairly common for factory Colt mags to only puch the slide stop up partically after the last round.  You might have weak mag srpings, or maybe just followers that are not properly shaped, or even a slide stop with a lug that is undersized.

There are other things that might cause it, such as a burr caused in the slide stop notch on the slide from improper re-assembly.  Also, like I mentioned, the slide stop might fit very tightly in either the frame or be rubbing due to excessively tight fit of the link/lugs.  Youcould theoreticlly have an oversprung gun too, but you would probably see some FTE problems as well.

Here are a few questions.  What mags are you using?  Are they the same age as the gun?  Is the gun relatively clean?   Is the slide stop original?  Is the recoil spring original or is it heavier?

I bought the Colt from a local gunshop who sold it as a new pistol. Everything's bone-stock on the pistol, with the exception of the handgrip panels. I did as you suggested and checked the depth of the engagement of the slide lock to the slide notch. It only seats partially in the seat, each and everytime. I then took off the slide and, with mag inserted, looked at how the lower plate of the mag follower engaged the slide lock. I shot it quite a bit yesterday, but it was clean when I started and was noticing the problem early on. The mags are Colt 8-round'ers that came with the pistol. There were no feeding problems at all during the day, but one occurrence where the slide failed to lock on an empty mag. The mag springs are plenty firm, from what I can tell so I'm looking into the burr possibility. So far, I can't see anything obvious. I do appreciate the advice and thank you for it!

If you get a chance, try the gun with some other mags.  Borrow some from a friend if possible.  I would suggest Wilson Combat 7 rounders or Colt 7 rounders.  The followers in 8 round mags fail to push up the slide stop all the way sometimes.  Let us know how it turns out.  Without going through the gun, it's hard to tell.  Hopefully it's just the mags.