Rifle Scopes There must be a formula..

[ROLEXrifleman]

Seriously, I just cant sleep and I'm spinning my wheels...

Is there / what would the formula be for finding a way to sight in your scope without ever taking a shot?


For example say we take know variables:
O MOA base
0 MOA Rings
175gr projectile at 2600FPS at the muzzle
Mechanicaly centered scope
Bullseye at 100 yards

What variables are we missing to try and solve the equation if even possible? I'd like to take my rifle out and prove it. Any math geniuses out there that can figure this out?

 

[dmg308]

Re: There must be a formula..

Its impossible because you have to take into acount base alignment and much more important your barrel cast off.A properly fitted match barrel has the high side of the barrel timed at 12 o'clock but even that has to many variables.If its a factory barrel it can be in any direction.

 

[tt350z]

Re: There must be a formula..

Assuming if everything is also in perfect alignment (which probably never happens)

Height over bore

With a HOB of 1.5'' +4MOA might be close to a 100 yard zero.

It's dropping 2.7'' at 100yard from the muzzle + the 1.5'' HOB brings you to 4.2'' difference at 100 yards.

ETA: My Viper has 64.5 MOA of elevation. Mechanical zero is 32.25 MOA + 20 MOA base. That should leave me with 52.25 MOA left over in theory.

After zeroing @ 100yds. I have 53.25 MOA left over using 168gr @ 2675 FPS

 

[ROLEXrifleman]

Re: There must be a formula..

Height Over Bore is somethig i'd have to measure once I put the scope on teh gun.

factory AI AT, 0 MOA AI dovetail base, NF NXS 12-42x56

 

[rjroberts]

Re: There must be a formula..

I would just underscore what dmg308 said. Anything manufactured has some variation, even when within specifications. Even if the scope optical axis, rings and base all align perfectly, the machining of the mounting surface with relation to the bore axis can be off. Perhaps only a slight amount but consider that difference at the muzzle vs. 1000 meters. Even the crowning of the barrel, a completely mechanical act, will have an effect on the travel. Ultimately, you need to sight. I laser sight to the range of the laser but on the range, while it's on paper, it's not aligned until I walk it in.