Sight Height

[Beelzebub]

Have a new RPR with a 56mm scope. Had to buy a pair of X-High rings to get the front of the scope to clear the fore end.

Just finished breaking in the barrel properly and now ready to do some load development and sighting in.

One of the questions on the ballistics calculator is sight height. So, best I can figure is that it is 1.6" from center of scope (30 mm) to the bottom of the rings where they sit on the top of the 20 MOA rail. I am "guessing" that sight height would be 1.70 or better. Anyone have the exact magic number to plug into this question on the calculator?

Thanks in advance.
B

 

[bill123]

Measure center of bore to center of ocular lens and aim to get within 1/4" of actual.

My OCD method:
Remove cap on ocular end of scope.
cover that end w masking tape (no tape on lens).
Measure to the center of the tape on the ocular & mark it.
Close the bolt.
Measure with calipers from the mark on the tape to the center of the end of the bolt.
Bolt and ocular will probably not be on same plane, but close enough.

 

[Bravo 4]

I can understand the desire to want everything as perfect as possible to eliminate any variables, but this one you don't need 100% exact. I just ran the numbers on my ballistic ap and a .5" change in sight height would equal a 10 fps change in velocity with my .338 RUM @ 800 yards.
Measure it till you are blue in the face if you want, but in this case close enough really is close enough. Nothing to stress over.
I'm not saying I would be happy with .5" off, but you don't need to measure to the any extremes. Put some calipers up to it (even a ruler or tape measure), measure center scope tube to center bolt, confirm it, input the number into your ballistic call, and go shoot.

 

[kyron]

Bravo 4 is right there are likely as many ways to take that measurement as there are shooters that know they need to take it.

Main thing to remember is it is from center of optic to center of bore. Keep that in mind and you will be fine

 

[Beelzebub]

You would think Ruger would be able to provide the distance from center of boar to the top of the 20 MOA rail. Especially since all three calibers are the same case will 3 calibers.

CS didn't seem to have a clue what I was asking them or why.

Thanks guys. I'll throw some calipers on it and eye ball it.

B

 

[toliver]

I take half the diameter of bolt and scope, add together, then measure distance from bolt to scope and add that to the previous result. Quick with a set of calipers.

 

[Beelzebub]

I've been meaning to get back on here and thank everyone that offered suggestions. Thank you.

Now, This sounds sure sounds high, but they say numbers never lie. I haven't plugged this number into the calculator yet. Does this sound/look about right to your "more mature" shooters? ;-)

 

[WildRose]

I've been meaning to get back on here and thank everyone that offered suggestions. Thank you.

Now, This sounds sure sounds high, but they say numbers never lie. I haven't plugged this number into the calculator yet. Does this sound/look about right to your "more mature" shooters? ;-)

A picture is worth a thousand words.

That's going to be about as close to exact as you're going to get and you can't be far enough off measuring that way to have it show up noticeably in your calculations.

 

[Beelzebub]

A picture is worth a thousand words.

That's going to be about as close to exact as you're going to get and you can't be far enough off measuring that way to have it show up noticeably in your calculations.

XXXXXXXXXXXXXXXXXX

Thank you for your service, Brother.

Lee