Sight height above bore

[Richard Coody]

We all need this measurement when using a ballistic calculator. Lots of methods to find this measurement. With all the nifty tools available for shooters and reloaders it is surprising to me that no one has invented a tool to measure this quickly and accurately.

Just thinking about it I was thinking a simple jig could be made to do this. Say a set of mandrels that would fit the bore of.different calibers. Stick your bore guide into your rifle. Pick the mandrel that fits in the bore guide. Mandrel attaches to a caliper type device. The calipers are used to find the center of the eyepiece or ocular lens. A little pointer at the center of the ocular measurement could give you your scope height.

I think it would be more simple to build than explain. I also think it would sell. We love measuring tools.

 

[std7mag]

1/2 diameter of objective, 1/2 diameter of barrel under objective, measure from objective to barrel.
3 measurements, that can be done fairly quickly.
If you build a tool, it will open up ways for people to not understand how to use it.

 

[Big Mc]

1/2 diameter of objective, 1/2 diameter of barrel under objective, measure from objective to barrel.
3 measurements, that can be done fairly quickly.
If you build a tool, it will open up ways for people to not understand how to use it.

That,s Right Tommy Mc

 

[Medic505]

A tape measure and an eyeball works very well. It's not rocket science.

 

[Rob01]

Yeah not rocket science at all. Just measure from center of bore to center of wind age knob. Doesn’t matter is 0, 20 or 40 moa base. Been doing it this way for decades and the number works.

 

[Fuj]

1/2 diameter of objective, 1/2 diameter of barrel under objective, measure from objective to barrel.
3 measurements, that can be done fairly quickly.
If you build a tool, it will open up ways for people to not understand how to use it.

Yes Sir !! The kiss principle works for me. I always take those
measurements and log them in the rifles dope book along with
any MOA configurations on the scope base.

 

[Kracken McGraw]

A tape measure and an eyeball works very well. It's not rocket science.

Yes, mines a free yard stick from the lumber yard. Take the bolt out and put stick flat against half of the objective with end zero measurement at the bore center.

 

[Ackman]

Don't make something simple into something difficult. Pull the bolt back to where it's below the scope bell. Measure center to center of each one.

 

[MikeT49]

1/2 scope tube OD + 1/2 bolt body OD + measured distance from bottom of scope tube to top of bolt body.

 

[std7mag]

Don't make something simple into something difficult. Pull the bolt back to where it's below the scope bell. Measure center to center of each one.

Your center, or my center?

Most ballistic calculators call for the objective lense, not the occular.
So you'd be measuring to the wrong end of the scope.

 

[Rob01]

Measure at the windage knob in center. It will do what you need for a ballistic program. As long as you are within about .25” you will be good. No need to be to the third decimal point for the sight above bore.

 

[Kracken McGraw]

Your center, or my center?

Most ballistic calculators call for the objective lense, not the occular.
So you'd be measuring to the wrong end of the scope.

Hmm, never thought about it. I always took the measure where the reticle crossed the rule looking through the objective.

 

[Richard Coody]

Well I guess you guys are right. You don't need no stinking tool. Still think it would be cool though.

I put a bore guide in and ran a cleaning rod through it from the muzzle. Measured with calipers. Did a little math and came up with 1.74"

Eyeballed center of bolt to center of windage knob. Came up with 1.75"

 

[gilream]

We all need this measurement when using a ballistic calculator. Lots of methods to find this measurement. With all the nifty tools available for shooters and reloaders it is surprising to me that no one has invented a tool to measure this quickly and accurately.

Just thinking about it I was thinking a simple jig could be made to do this. Say a set of mandrels that would fit the bore of.different calibers. Stick your bore guide into your rifle. Pick the mandrel that fits in the bore guide. Mandrel attaches to a caliper type device. The calipers are used to find the center of the eyepiece or ocular lens. A little pointer at the center of the ocular measurement could give you your scope height.

I think it would be more simple to build than explain. I also think it would sell. We love measuring too

We all need this measurement when using a ballistic calculator. Lots of methods to find this measurement. With all the nifty tools available for shooters and reloaders it is surprising to me that no one has invented a tool to measure this quickly and accurately.

Just thinking about it I was thinking a simple jig could be made to do this. Say a set of mandrels that would fit the bore of.different calibers. Stick your bore guide into your rifle. Pick the mandrel that fits in the bore guide. Mandrel attaches to a caliper type device. The calipers are used to find the center of the eyepiece or ocular lens. A little pointer at the center of the ocular measurement could give you your scope height.

I think it would be more simple to build than explain. I also think it would sell. We love measuring tools.

Measure the objective lens diameter and divide by two, measure the barrel diameter directly under the bell of the scope and divide by two, measure the distance between the bottom of the objective lens and the top of the barrel. Add the three numbers together. This input has minimal importance anyway in your ballistics calculator ...if you are in the ballpark you will be fine.

 

[Charlie-NY]

Since almost everyone seems to be using tapered bases (often 20moa) does it matter whether you measure from the ocular end or the objective end? You obviously get a different measurement.

 

[Rob01]

As I said above measure at the windage knob and doesn’t matter base taper.

 

[Jarhead6870]

It can be complicated or as simple as measuring from the action's gas port directly above to the center of the scope tube or the joint of your ring cap; the measurement has some flexibility. I did a little number crunching for one of my rifle's on my ballistic app and it showed that at 1000 yards, the elevation difference is a little over an inch for the measurement difference of 1/8". I think most can eyeball the height to within 1/16" using a ruler thus the elevation differences are minimal.

Also, for those who shoot paper, any difference in elevation is lost in the noise when shooting sighters and making adjustments.

 

[FeMan]

I was shooting at a team tactical match last year and learned something new regarding this from my partner.

One stage had a tree of #2 pencils sticking out horizontal at 25 yards or so. The teams had to shoot and break two pencils before moving on. This stage had unlimited round count. The backstop was at 1k yards so you had no target feedback. I was amazed at how many teams could not get through the pencil part of the stage in the allotted time of 90 seconds and zeroed the stage. We cleaned the stage thanks to my buddy who went 2 for 2 on the pencils. I missed like everyone else.

When I asked him how he managed that, he said its all in setting your Kestrel up with the "correct" scope height. He explained that if you measure it and use that, you will miss every time. He said you need to: get a solid zero and set your Kestrel up with that and an assumed scope height. Then go shoot at a very close target (like 20 to 25 yards) and adjust your turret until you are hitting exactly where you are aiming. Then go back to the Kestrel and adjust your scope height in the program until it gives you the correct elevation you dialed for the close target.

I've never had an issue using the measurement technique that most are describing. Unless you want to shoot a fly at close range it probably doesn't matter, but I did find it interesting.

 

[Rob01]

Guess that's one way to do it but if you have a proper sight height measured like I posted above you should be able to hit those without a problem. I have shot dots about that size down to 11 feet back when matches actually had shots like that with measuring like I posted above. Getting in real close will show error as i believe it was around 13 mils of up to hit at 11 feet.

 

[JEFFPPC]

Anyone needing a special tool or jig to measure the center of the bore to the center of the scope should have all reloading supplies and firearms taken away from them. They are not competent to have potentially dangerous toys.