Its a threaded hole for a set screw but was done by an amateur since its off-center. The corresponding gouge on the bottom of the sight was caused by the raised edges of the hole, or perhaps the set screw was installed and adjusted to make the sight tight when installed. If there was ever a set screw in it, it was overtightened which pulled up that edge. That's why it has go on from the left and go off to the left. Its not an acceptable arrangement. Will it stay put long enough to sight it in and mark the rear sight? The hillbilly way then would be to take the sight out, peen down the edge around that hole, peen the edges of the sight until you get it tight, and line it up with the mark.
Somebody really worked that slide over!

 

Thanks 1saxman. While the edge appears lift up in the pic, it is completely flat. Also, the right side of the 2-dot sight was broken off from some previous owner…hence my need to replace it.
I just wasn’t sure why that round divot even existed. I’ll push to new sight into place as close to center as possible…then drift as need for accuracy at the range.
we’ll see if the new sight stays in place.

 

Its a threaded hole for a set screw but was done by an amateur since its off-center. The corresponding gouge on the bottom of the sight was caused by the raised edges of the hole, or perhaps the set screw was installed and adjusted to make the sight tight when installed. If there was ever a set screw in it, it was overtightened which pulled up that edge. That's why it has go on from the left and go off to the left. Its not an acceptable arrangement. Will it stay put long enough to sight it in and mark the rear sight? The hillbilly way then would be to take the sight out, peen down the edge around that hole, peen the edges of the sight until you get it tight, and line it up with the mark.
Somebody really worked that slide over!

Thanks 1saxman. While the edge appears lift up in the pic, it is completely flat. Also, the right side of the 2-dot sight was broken off from some previous owner…hence my need to replace it.
I just wasn’t sure why that round divot even existed. I’ll push to new sight into place as close to center as possible…then drift as need for accuracy at the range.
we’ll see if the new sight stays in place.

 

You do have to clean up that sight channel… previous owner(s) didn’t do you any favors. The guys at XS sights are helpful if you go that route.

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xssights.com

 

That doesn't look like a set screw hole to me, but rather a punch mark. 1911 rear sights are supposed to be removed/installed from the right side. The fact that you easily took yours off from the left tells me the sight was really loose in its dovetail, which explains the punch mark in the bottom of the dovetail. The old Army repair depot method of tightening a loose rear sight was to whack the bottom of the dovetail with a center punch and displace some extra metal to help tighten up the fit of the sight.

 

DSK is correct. A good sight is the Harrison Design rear sight which in fact does have a set screw. I would clean up the slot at the punch mark, then install the Harrison Design sight. If the dovetail slot is loose- I usually zero the gun, then I make a small spot with a drill on the dovetail flat in which the sight set screw can "nest". This will hold its position- along with a little blue loctite on the screw.

 

Thanks All. I have a standard two blade sight for the replacement. I think there are some disagreements on the forums about “Colt” 1911 rear sight direction. My understanding is that most 1911s exit to the right. However, Colt and perhaps some other mfgs, exit to the left. I doubt that matters at this point. I know I will have the sight installed from left to right.
Note: the sight did not come out easy. I used a pusher (Accucraft)…then changed to a brass punch since the Accucraft was just not doing it.
I’ll install the new sight. Test a bit to see if it stays in place. My guess is that it will.
Overall…I just wanted to make sure there was ot some sort of pin or screw from the bottom of the slide that needed to be addressed. Sounds like general consensus is that there is NO protrusion, or other, from underneath. I’ll update once I have installed the new sight.
Thank you All for your thoughts and guidance.

 

Whoever you talked to doesn't know what they're saying. Colt has always followed the original Ordnance Department drawings, and the Army manuals all say to remove/install from the right. Unfortunately a lot of the people who answer the phone at Colt are clueless about the stuff they sell.

 

It wouldn’t be a surprise if someone if I had a different answer if I talked to someone else. There seems to be quite a difference of opinion on the this forum…in both directions.
(https://www.1911forum.com/threads/colt-rear-sight-removal.481727/)

At this point, I have already installed the sight and seems to have gone on fairly smooth, tightening up as I continued to set to the right. It feels pretty stout. Anxious to get some rounds through it.
I sure appreciate the dialog.
Thanks All!!