When is 20MoA not 20MoA?

[Delivery]

I had a 20MoA Aken mount on my pic rail but I really needed a QD function so I can remove the sight when storing and because I already had DOPE for the Arken based on the 20MoA cant I was looking for a new mount with 20MoA so I can use all the old DOPE values
Simples

Thankfully just because I wanted to double check I shot a couple of rounds using the Arken then switched over to the new 20MoA AD mount with the same sight on the same turret settings

Interestingly although I didn’t expect the two to be identical I did expect them to be close but I was surprised to see not only about the best part of an inch difference in elevation (at less than 100 yd) and the Arken shots landed to the left of the PoA and the AD shots landed to the right of the PoA

I will look into this a bit further and re zero to get it perfectly lined up and see what the behaviour and return to zero is like using the AD when it’s removed and refitted a few times but other QDs I’ve had have always have been pretty good therefore I’m surprised there’s such a big difference between the two 20MoA mounts

Anyone else experienced similar?

D

 

[jcampbellsmith]

I'm surprised that they are that close.
Regards
JCS

 

[nun_hunter]

A fraction of a mm at the scope end would lead to 1moa difference quite easily, so as above I'm impressed they were that close. When swapping scopes and rings/rails previously they have been out by considerably further.

 

[Delivery]

I’ve never done an identical swap like that before so maybe I should have not has such high expectations

 

[Malxwal]

They would have to be dimensionally identical in every aspect. Alas life is not that easy.

 

[Delivery]

They would have to be dimensionally identical in every aspect.

I was thinking for the reasonably large sums of money they would be, but I wasn’t considering the maths and trig around potentially slightly different heights or something
Thanks for the input as ever SD to the rescue!

 

[Donkey Basher]

A fraction of a mm at the scope end would lead to 1moa difference quite easily, so as above I'm impressed they were that close. When swapping scopes and rings/rails previously they have been out by considerably further.

To be precise a 1” (rounded to 25mm) difference at 100m equates to an error of 0.05mm on a 200mm long base on the rifle.