Mirror on a mantle

[tinpanalley]

The spackle wouldn't and any structural integrity.

Ok, that's what I thought. Plus, removing them later through that spackle could tear out an even bigger chunk of plaster, I imagine.

My concerns with the current setup is that the head of the screw might not have enough 'lip' to keep the wire truly secure behind it.

It's too late for me now to unscrew these and add a washer, right? Once concrete screws go in that's it, you can' re-set them?

Also, there's no clamping force exerted between the wall and the head. Is it solid in the hole? The old hole may be compromised. You can tell if you sink the screw but it just spins and doesn't bite.

Oh, it's solid. I mean the tip wiggles by a mm or so if you use force but I think that's due to the 1/4" sticking out and the 5/8" in the loose plaster. The one on the right can go a bit farther because I drilled the hole a bit too far.
When you say "the old hole", what are you referring to? The one below? That hole goes down on a 45degree angle not on a straight angle into the wall. And it's far enough down.

 

[ISAslot]

Ok, that's what I thought. Plus, removing them later through that spackle could tear out an even bigger chunk of plaster, I imagine.
It's too late for me now to unscrew these and add a washer, right? Once concrete screws go in that's it, you can' re-set them?
Oh, it's solid. I mean the tip wiggles by a mm or so if you use force but I think that's due to the 1/4" sticking out and the 5/8" in the loose plaster. The one on the right can go a bit farther because I drilled the hole a bit too far.
When you say "the old hole", what are you referring to? The one below? That hole goes down on a 45degree angle not on a straight angle into the wall. And it's far enough down.

The old hole is the one it's currently in. Though not recommended, you may be able to unscrew and use the holes again. You'll be able to tell if this will work because they will still 'bite' and not spin.

 

[tinpanalley]

The old hole is the one it's currently in. Though not recommended, you may be able to unscrew and use the holes again. You'll be able to tell if this will work because they will still 'bite' and not spin.

I'm going to take some wide thin washers I have, make a single cut into the center from the outside and slip that onto the screw so that the cable sits between the washer and the wall.