[romulus]

I'd like to install GR sights on one of my Rem870s. How do you locate top dead center on the barrel? On the receiver? What's an acceptable tolerance as far as being off center to some extent (if the sights are canted a thousandth or two will it affect POI?)

Thanks

[Traveler]

When set square into a holding fixture you use a break away to find top dead center. Especially on tapered cylinders like barrels. The other way is to set the height of the cutter and change it every time you pass under. Then you mark the position, drill and tap. All in one set up.

If you don't use a mill, and you don't make sure it's square, you invariably set the holes crooked and off, and then pay someone who knows what they are doing to correct your XXXX up. Or you live with sights that are not dead on. (Well, if you hold the gun slightly canted it works).

[romulus]

I was planning on sweating on the sights...does that change anything?

[Traveler]

No. Still find center the same way. You can use a stub of a pencil instead of a cutter in the head. Make a pencil line btween to center points down the barrel. Mark center of the sight if it's not already marked. Use machinist square to make sure it's square and a level (I like the magnetic ones).

When soldering I like to make sure that whatever setup I use is square to the work so that I can see the results as I work. If you use some form of indicator that is 8-12" long you will see any offset in a hurry.

[romulus]

Thanks

[Sunray]

Take the existing bluing off first and use silver solder only. Otherwise the new sight won't stay put. I've always eyeballed the center but I seem to have an eye for doing that. Brownell's has tools for this if I'm not confused.

[kentucky bucky]

I Know how to find top dead center in a '62 Nova. :D

[romulus]

Sunray, isn't there a danger of warpage or altering the heat-tratment of a barrel or receiver when silver soldering? I thought SS required exteremely high temps...

Thanks for all your replies. Good one about the Chevy :p