Setting you ‘scope mechanical zero.

[ovenpaa]

I dislike having a mechanical zero that is not the same as my actual zero, by that I mean I mean for me there is nothing worse than winding your elevation turret down to a 100m/200m zero or whatever and knowing there are another 12 clicks to go, in stress situations it is nice to know that if I wind the drum down when it stops it is at my chosen zero. My AI is good in this respect, with the S&B PMII and a 28 minute rail it is on zero at 100m with only one click lost. Not so with my Nightforce so I set the rifle to zero (200m) and then measured the gap between the top of the body and the bottom of the drum and turned a spacer to fit so I know that when I wind the turret down and it stops it is zero minus one click. Nice because it means I can never loose my zero.

With the Kahles K312 which uses Apel rings and straight mounts I had two options, either pack the rear mount up which puts unnecessary stress on the body or keep it parallel which looses a lot of elevation and means I am a turn and a half off my mechanical zero. There was a third option, pack the rear to get to my mechanical zero, measure the packing, then measure the distance between the extremities of the rings and machine a taper to suit, fit it and cut out the middle section so I know I have a stress free mechanical zero, plus bed the lower half of the rings to the ‘scope tube with JB Weld and job done.

So is it only me that has a hang up about mechanical zeroes or does anyone else do anything similar?.................

[Scotsgun]

Just you mate

We learned on an alpine course that the 'zero isn't necessarily always the zero.'

[Gun Pimp]

Dave,
Isn't that why tapered scope-rails were invented?
Cheers
Vince

[ovenpaa]

Dave,
Isn't that why tapered scope-rails were invented?
Cheers
Vince

Yes however some rifles/mounts do not allow for tapered rails, Apel rings are a good example and some tapered rails are not at the correct angle to get to a close mechanical zero

[20series]

My Remmy has a 20moa rail and my mech zero is 8 moa below my 100 yard load zero

[Porcupine]

I may have completely misunderstood the issue here but, isn't this solved by loosening the locking cap on your turret, rotating the numbered ring so that the number zero on this ring matches the come-up line of your 100m (or whatever) zero (the come-up lines staying fixed while you rotate the ring) and then tightening the locking cap back down. You are then dialed in on your 100m zero which now corresponds to the 'zero' on the numbered ring. So you can then adjust the elevation/windage a full revolution, or whatever, away from zero to make a longer range shot, and simply return to the 100m zero by winding back to the number zero - as opposed to having to remember that your 100m zero is X clicks before the number zero.

[Scotsgun]

I may have completely misunderstood the issue here ............

Yup, think so. He wants the absolute bottom travel of the elevation turret to correspond to 100yds, not you recalibrating the turret to read 100yds because you altered it (e.g. at say 100yds he can't physically turn the turret any lower).

However, the point i made (only lightly) was that a rifle zero'd too 100yds will shoot high if shooting up or downhill and as such may require fine' tuning. I attended an alpine course once where some of the shorts they'd prepared, deliberately short and long were as much as 45-60 degrees!

[Porcupine]

Ah I get you now. I was a little confused because my understanding of 'mechanical zero' was not where the bottom of your scope's internal adjustment is, but where the 'middle' of your scope's internal adjustment is e.g. if you have a 100moa scope the mechanical zero would be 50moa up from the bottom (or down from the top, however you want to look at it).

You can, as has been mentioned, get tapered rails and also rings with shims. But these will only give you up to maybe 30moa of extra mechanical elevation so if you have a 100moa rifle with a 100 yard zero at 55moa from the bottom of the internal adjustment the shims are only going to bring you down to 25moa up from the bottom instead of the zero that you want. On the other hand if you have a 60moa scope with a 100 yard zero dead on at 30moa from the bottom then you'll have just enough shim to get it right down to the bottom.