Finding Top of a Barrel to Drill & Tap

[esq_stu]

I want to cut down a plain 20 gauge barrel from 28 inch to about 20 inch and install a bead or other front sight.

Is there a special tool or technique to find the location to drill the barrel for a bead sight? Can anyone suggest a link to a procedure?

Thanks.

 

[Jayb]

Before you cut the barrel off, use the current bead to mark center of the barrel for the new hole.......

Lay the barrel down on a flat surface with the bead at either 9 o'clock, or 3 o'clock.

clamp it, or make sure it doesn't move

take a 4" long piece of standard 2x4 and lay the wide side on the flat surface and press the side up against the current bead, just enough to mark the wood

using that mark as a guide, drill a hole in the side of the 2x4 big enough for a pencil

stick a short pencil in the hole, (point out )

check it against the original bead to see if the pencil point lines up with the center of the bead..... if it does....

slide the block down the barrel and using the pencil point, mark the barrel as you see fit...........

Kinda primitive, but it works..

 

[jmorris]

You can also take a short section of ¾”angle and with the bead removed, place the barrel into it line the edge up with the preexisting hole, and then use silver pensile to run a line lengthwise down the barrel. That is if you don’t have a mill/drill with an X/Y table that would allow you to locate from the original hole then travel “X” distance down the barrel where you want the new hole, and then drill.

 

[esq_stu]

thanks!