TC Hunter tang sight elevation adjustment question

[Crossed Arrows]

I've picked up a couple of Thompson Center Hunter tang sights, but I cannot find instructions for them.  Not too complicated, I just need to know what the elevation adjustment is.  I know that you have to loosen the back bolt with an allen wrench, then turn the top bolt with the same wrench to adjust the elevation, but I don't know what a full turn of that elevation bolt equals.  Of course, you then have to tighten the back bolt again.

I have one of these tang sights on a Lyman Great Plains rifle and I'm getting ready to sell the other one in my neverending attempt to clean house.

[willyr]

There would be a lot of variables involved- sight radius for one. I have used those sights for years and really like them. The only way to answer your question is to tell you to shoot the gun, make an ajustment, then shoot it some more. This is kinda like " what's a good starting load for...."
Bill

[Dave Faletti]

Measure the sight radius and thread pitch on the adjustment screw.

[Standing Bear]

This works for any iron sighted gun that I know of.  It is easy math.

All distances are in inches.

The formula is M/S = I/R  plug in the measurements and solve for M.

1.  The distance between the two sights  (call it S for sight radius)
2.  The distance you want to move the point of impact (I for impact)
3.  The range at which you want to move that amount of POI (R for range)
4.  Amount to move either sight or or total to move both (M for move)

To move the POI 3 1/4 inches at 3600" (thats 100 yards) on a gun that has 25.7" between the sights.

M =
I = 3.25
R = 3600
S = 25.7

M/25.7 = 3.25/3600
M=25.7 X 3.25/3600
M = .0232

Move the sights  .023".

[SCLoyalist]

A reasonable guess, based on the threads per inch I've seen on other TC rear sight elevation screws, is that the screw is threaded around 20 tpi, so one complete revolution of the screw would raise or lower the rear sight height by about .050".   TC Compton's formula is a good one.  I'd expect a 32" long barrel gun like a  GPR to have a 36" sight radius with a tang mounted sight, and one complete revolution of elevating screw to result in a 5" point of impact change at 100 yds.    Keep in mind, though, that when you loosen that back bolt in the back and retighten it, something may shift a little, depending on the sight's design, so you're still going to have to do Bill R's verification.

[Crossed Arrows]

Great answers guys.  Many thanks.

More and more I realize why the math teacher wanted me to do my homework.

[Pete G.]

It depends on which you like better; shooting or math.
Don't bother with the homework. Shoot a group, adjust the sight one full turn and shoot another group. The distance between the two will tell you exactly how much adjustment you need.