1911 slide-stop malfunction


January 23, 2012, 02:46 PM
I have now twice encountered a malfunction with the slide-stop on my Series 70 Colt 1911. It first occurred some 2 years ago when the slide-stop worked loose while firing and came about a quarter of an inch out, resulting in a totally jammed pistol.

I put in a new slide-stop and everything was OK until about a week ago when the same thing happened (unfortunately in the middle of an IDPA shoot). I have now replaced the original slide-stop and yesterday shot about 100 rounds with no problems.

I have searched extensively through 1911 literature, including the ever helpful 1911 Consolidated Thread, without getting anywhere. Local "experts" have suggested either that I reassembled the pistol incorrectly after cleaning or that I was somehow pressing against the right side end of the slide stop. Both possibilities can be discarded - there is only one way an 1911 can be assembled and as a right handed shooter I could not possibly have been pressing against the "non-lever" end of the slide stop.

As I understand it there is only one position in the 1911's cycle when the slide-stop could come out and that is when the indent in the slide is aligned with lug on the top of the slide-stop.

Advice and comment will be welcome.

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January 23, 2012, 02:58 PM
There is only one place on the slide where a slide stop can come out.

However, it is possible for a frame to have the hole the slide stop sticks through into the mag well cut out of spec, or too deep.

That will allow the slide stop to drop down far enough to clear the slide at any point.

I suppose it could also be possible for the slide or frame rails to be cut or worn so loose the slide is riding high enough for the stop to clear it, although I have never seen it happen.

Assemble the gun without the recoil spring.
Then try pressing on the right side end while slowly pulling the slide back and see if there is any other place besides at the disassembly notch where you can press it out.

If there is, you have a bad frame.

PS: What type of bullet shape are you shooting?
Does the gun ever lock open before the mag is empty?


January 24, 2012, 11:09 AM
Thanks rcmodel for for your helpful reply. I have tested the gun with the recoil spring out as suggested and there is only one point where the slide-stop comes out and that is when in line with the disassembly notch.

I am using 200gr cast round-nose over a charge of 5.8gr of Somchem MS200 which seems to be reasonably similar to Hercules Red Dot in the US.

I have had various malfunction problems including smoke-stacks and gun locking open with the last round lying loose on top of the mag. These I believe were ammo related and seem to have (hopefully) been resolved by careful selection of the correct case length, use of a factory crimp die and setting a COL slightly longer than that recommended. The "no-jams" shoot in my original post is the most reliably this gun has shot since I got it.

I feel I am on the right track re ammo but would really like to resolve the slide-stop malfunction. A thought that had occurred to me is that the gun is fitted with Pachmeyer grips with a built-in plunger tube and maybe this was angled wrongly and the plunger was tending to push the slide-stop out during the firing cycle. Comparing this with other guns it seems unlikely.

January 24, 2012, 12:10 PM
Pachmeyer grips with a built-in plunger tubeThat is a new one on me.
Don't recall ever seeing anything like that.

But, it would be highly suspect, IMO.

200gr cast round-noseCarefully inspect the bottom inside edge of the slide stop that projects into the magazine.
Look for lead smears on the bottom outside edge of it.

It might be possible that your RN bullet is fuller diameter further out of the case, or has less ogive radius then a 230 GI bullet shape.
As such, the round coming up in the magazine might be whacking the slide stop in just the right place to knock it out of the take-down notch in the slide.
That is pretty far-fetched too, but it is worth a look.

If you do find lead marks on it?
Bevel the bottom edge and polish it so the bullets can't hit it.

Or change bullet shapes.

The other thing you could do is use a dental bur and make a small depression on the back of the slide stop the plunger can fit in with the slide stop down.
It can't be too deep or the mag follower will not be able to over-ride it and lock the gun opon on the last shot.

Here is a tool made to do the same thing you can do with a dental bur and a rotory tool if you are careful.

But I would not do it with a grip mounted plunger tube, as it very likely would be in the wrong place if you had a real plunger tube attached to the frame.


January 24, 2012, 12:53 PM
Check to see of the barrel is being stopped by the link. Sometimes that can push the stop out.

Do this:

Remove the slidestop partway and let the arm hang vertically. Push the stop back into the frame as far as it will go.

Press the muzzle straight into the edge of a heavy table or bench until the slide and barrel stop solidly. Hold it firmly and see if the slidestop will swing freely. If it gets in a bind, the link is stopping the barrel.

Possible reasons:

Short link. Vertical impact surface located too far to the rear. Rear edge of the lower barrel lug located too far forward. Link pin mislocated in the lug. Slidestop pin mislocated in the frame.

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