Haven't tried it with the Lyman sight, but there's an easy way to get the hole for a TC Hunter Peep perfectly located every time. It would be easy to see with a picture or two, but I don't have pictures so I'll take my best shot with words.

First, you need a drill bit that exactly fits the front hole of the sight. I forget what size that is but you can try a few bits from you set to see which one fits right. A bit that's a tiny bit larger than the sight hole is OK, but one that is noticeably smaller is not.

1. Remove the tang from the gun.

2. Using the rear tang screw, secure the sight and tang to a block of wood. I use a six inch length of 2" x 2" pine, but a short length of 2 x 4 would work as well. The tang should sit flat against the block lengthwise, with the rear of the hook face butted against the end of the block.

3. Place a small C-clamp crosswise near the front hole of the sight to hold the sight and tang in perfect alignment. A 2" or 3" clamp works best. The bearing surfaces of the clamp should contact both the tang and the sight base on each side.

4. Position the drill bit into the front sight base hole and drill a 1/8" deep dimple into the tang. If you bit is slightly larger than the sight base hole you will be drilling through the tapered bottom of that hole also. That's no big deal so long as it's only slightly larger.

5. Now you have a perfectly centered funnel shaped dimple started in the tang, and will be able to use that dimple to position the smaller bit you're going to use for tapping. It's far superior to trying to use a center punch to mark your position.

I hope that made sense.