Rifle Scopes Question about 2 S&B PMII remaining elevation on same rifle

[Canuck1977]

Good morning to all, It's Saturday morning and I have a maybe dumb question.... brain is not functioning at 100% today. I just changed scope from an S&B 3-20x50mm for a 5-25x56mm. Using same Spuhr SP4002 mount on the exact same rail location. Only opened up the rings to swap the scopes.

Here is the question: I had 23 mils left of elevation with the 3-20 and now only have 19.8 mils of remaining elevation with the 5-25 with a 100 yards zero... Why???

the axis of the scope should be the same no???

let me know what you think....

Cheers to all

 

[pell1203]

In theory perhaps, but in reality you have different zoom ratios, tubes, internal mechanicals, optical elements, optical centering and alignment, and could even have differences in the way each scope interacts with the mount.

Would have been surprised if you'd gotten the same numbers. Too many variables to have them come out the same. Most likely tolerance stacking on both scopes accounting for the differences.

 

[redneckbmxer24]

It's just a difference of internal travel in the two different models is all, the 3-20 probably has a little more travel. Right around 19 mils (+/- 1) is what I usually end up with for a S&B 5-25 with 20MOA bases. 40MOA total will definitely give you a 100 yard zero and both full turns on the knob, I've mounted a few in 45MOA AI mounts and also had no problem getting a 100 yard zero. I just mounted one on a 30MOA base for the first time and I've got 25.1mils after zero so it's almost the entire travel.

Based on my experiences I'd say 35-45MOA of total cant between both the base and mount should give you the full travel for a 5-25 model and allow 100 yard zero.

 

[918v]

My 8-25 has 21.5 mils remaining on my 24moa mount. The 3-20 has more internal travel.