180 AB bc

RockyMtnMT

Official LRH Sponsor
Joined
Mar 25, 2007
Messages
5,467
Location
Montana
Hey guys,

Anybody got a real world bc on the .308 cal 180 AB running around 3400fps. Shot some this weekend and can't get the drops to match published bc. Just want to know if I have some other data wrong or if it is the bc.

Thanks

Steve
 

RockyMtnMT

Official LRH Sponsor
Joined
Mar 25, 2007
Messages
5,467
Location
Montana
Having to run .43 bc to match the drop at 980 yrds. It really makes no sense. Everything else has to be so far off from the collected data to get the drop to work. Velocity and zero yardage are the two big ones. Everything else makes only very small changes. Where could I have gone wrong?

Steve
 

Ridgerunner665

Well-Known Member
Joined
Sep 15, 2008
Messages
553
Are you taking into account all the atmospheric data? What are you using to generate the drop data? A lot of little things add up to big things...


Scope height or muzzle velocity would be the first things I double checked...chrono's can be contrary gadgets at times.'


Could even be the load itself...if you used a powder that is prone to changes with temperature...
 

RockyMtnMT

Official LRH Sponsor
Joined
Mar 25, 2007
Messages
5,467
Location
Montana
Are you taking into account all the atmospheric data? What are you using to generate the drop data? A lot of little things add up to big things...


Scope height or muzzle velocity would be the first things I double checked...chrono's can be contrary gadgets at times.'


Could even be the load itself...if you used a powder that is prone to changes with temperature...
Ballistic ftp on ipod, jbm, and another. All come in the same. Chrono reading is basically the same as another rifle with the same load. Scope height changes make very little change in the drop on the programs.

The only thing that I can make sense of is a the zero range being wrong. To match the drops I would have to be off by 5" at 300 yrds. That just wasn't the case. Chrony reading was at 3340fps, would have to be wrong by nearly 200fps to match the drop. That could be it. But other rifles shot on the same day ran ballistics fine with the same chrony.

Not a big deal. Just frustrating.

Steve
 

BryanLitz

<b>Official LRH Sponsor</b>
Joined
Mar 8, 2007
Messages
633
Have you verified that your scope is tracking true?

In other words, when you dial 30 MOA of elevation (for example), does your scope actually move your point of aim 30 MOA? It's common for scopes to not track true. Test at short range to verify.

Good luck,
-Bryan
 

RockyMtnMT

Official LRH Sponsor
Joined
Mar 25, 2007
Messages
5,467
Location
Montana
That makes the most sense. A guy always looks past the scope and assumes that it is doing what it should. Especially when you have others of the same model working fine.

Steve
 

Nightforce has great tracking capabilities, they are rugged, a bunch of elevation, holds zero forever, and reticles are designed for long range shooting. So if you are looking to shoot long distances constantly, then you need a scope that can take the abuse. -- gilmillan1


Culture Of Excellence At Nightforce Optics
By Len Backus

A high level of quality both in production and in service. Read More


Nightforce is such a solid combo of reticle, available elevation, glass that is good enough to shoot at the longest range you can dial. Nightforce has bullet proof construction that can handle the incidental horse rolling or some other rodeo action. -- bigngreen


Nightforce ATACR Scope Review
By Jeff Brozovich

The new NightForce ATACR is for sure a top choice for any long range shooter. Read More


The total package. Nightforce is the best I have used as far as turret feel and solid detents. I have never had one that didn't track right on and always return to zero. Nightforce NXS is the best value for everything I need. -- Broz


Nightforce Velocity 1000 Reticle Review
By Scott Shreve

I think Nightforce knocked it outta the park with this reticle! Read More

NightForce


Top