Wednesday, March 04, 2009
Scope Click Values
I have been using ballistics program for many years to estimate the trajectory of my airguns. I even wrote my own program for Windows with a very simple interface. However, none of the programs ever seemed to be very accurate at closer ranges like 10 or 11 yards. I just figured it was an estimation error in the programs calculation.
I remember many moons ago Rodney Boyce teaching me a really easy way to measure the actual click value of a scope. I don't remember the formula anymore but I figured out a pretty simple way to measure it and calculate the click value. It is pretty simple, just pick a close distance to shoot, say 15 or 20 yards, and record the distance. Measure out the distance to be accurate. Put out a target and shoot 5 or 10 shots into the target. Then click the scope up (or down) a number of clicks to get the groups apart and record the number of click of change. I used what I thought would be about 1 inch of clicks. Then shoot the same number of shots at the new setting. Then measure the distance between the groups and record it.
With these three values, the click can be calculated using the following formula:
D = distance to the target
c = number of click adjusted between groups
d = distance between the groups
click value = ((100 / D) * d) / c
Years ago I had tested my Baush & Lomb 6-24x scope and found it to be .125" per click just as specified. The Burris Signature 8-32x was specified at 8 click per MOA but they measured 6 clicks per MOA. Since measuring the click values way back then I just always used .125" per click for the Elite series scopes. Well I decided to check one of my current Elite 6-24x scopes tonight and found that it measures around .133" per click. That surprised me and make more sense that my numbers up close would be so far off. I didn't have time to plug in these values into trajectory program and then shoot test them. So, that gives me something to try in the next few days.
I remember many moons ago Rodney Boyce teaching me a really easy way to measure the actual click value of a scope. I don't remember the formula anymore but I figured out a pretty simple way to measure it and calculate the click value. It is pretty simple, just pick a close distance to shoot, say 15 or 20 yards, and record the distance. Measure out the distance to be accurate. Put out a target and shoot 5 or 10 shots into the target. Then click the scope up (or down) a number of clicks to get the groups apart and record the number of click of change. I used what I thought would be about 1 inch of clicks. Then shoot the same number of shots at the new setting. Then measure the distance between the groups and record it.
With these three values, the click can be calculated using the following formula:
D = distance to the target
c = number of click adjusted between groups
d = distance between the groups
click value = ((100 / D) * d) / c
Years ago I had tested my Baush & Lomb 6-24x scope and found it to be .125" per click just as specified. The Burris Signature 8-32x was specified at 8 click per MOA but they measured 6 clicks per MOA. Since measuring the click values way back then I just always used .125" per click for the Elite series scopes. Well I decided to check one of my current Elite 6-24x scopes tonight and found that it measures around .133" per click. That surprised me and make more sense that my numbers up close would be so far off. I didn't have time to plug in these values into trajectory program and then shoot test them. So, that gives me something to try in the next few days.
