Trying to set up a ballistic calculator here.

[DonaAna1]

The question is,

where does one measure scope height when one has a 20 MOA rail installed.

 

[lbc_PSI]

I've always used the front..even when there was a 20MOA rail involved..never had issues.

 

[ram2jeep]

Same here, front of the scope and haven't had any issues either...

 

[rc4fun]

Why wouldn't you use the center of the mounting points or the average of the front and back? It's not a huge difference has anyone tried using the different values and looking at the output to see the difference. How far downrange do I need to go before it makes a real world difference?

Just wondering, not trying to argue.

 

[lenweber2]

1/2 bell + 1/2 shroud + distance between = height. Never have a problem.

 

[18.13]

End of barrel to line of sight. Shoot a box as close to the end of barrel as possible 

 

[18.13]

https://airgunaccuracy.wordpress.com/chairgun-and-scope-height/

If you have any barrel droop you will be off just measuring up from barrel to scope 

 

[lbc_PSI]

For what it's worth, I tried the "ChariGun" method as outlined in the above link and essentially got the same results as measuring center of bore to center of scope. If there's a difference, it's in the thousandths and CG only measures to the hundredths.

The CG method might make sense if you have a gun where it's difficult to determine where center of bore is. 

On Edguns, center of bore is easy to measure on R5, R5M, Lelya, and Leshiy..just remove the moderator and there's the barrel..or in the case of the Leshiy, just break it open. Save a pellet and air..LOL