windage changes when swapping ammo

[ggiddy]

I have a scope zerod for brand1 of 5.45x39 and then change to brand2. There is windage and elevation change using brand2. In my very limited understanding of ballistics, I can guess the elevation change is from the velocity being different between brand1 and brand2, but what causes the windage change? Would different bullet weights, going from 64gr to 55gr, cause a windage shift?

 

[_Windrider_]

I have a scope zerod for brand1 of 5.45x39 and then change to brand2. There is windage and elevation change using brand2. In my very limited understanding of ballistics, I can guess the elevation change is from the velocity being different between brand1 and brand2, but what causes the windage change? Would different bullet weights, going from 64gr to 55gr, cause a windage shift?

Lighter bullet more susceptible to wind unless it’s going faster to compensate

 

[Sartori42]

I also wouldn't discount barrel harmonics. I have a Browning 22 WMR that throws 30g VMAX bullets 2 MOA right of everything else (mostly 40g. ammo). If you're going to zero your scope, that only works for the particular ammo you used to zero.

 

[ma smith]

...

 

[spife7980]

A windage change? I think you mean that there is a difference in the zero between two separate ammos? If so then... yeah. They are different and as such... they are different.

 

[Shootin Stuff]

I also wouldn't discount barrel harmonics.

Better not let dthomas see that.....

 

[hlee]

Better not let dthomas see that.....

Really? Why? I’ve got a 308 that when zeroed for 168 Amax bullets, shoots Barnes 168 TTX bullets 3” right at 100 yards. It ain’t the wind pushing them there. Both are hand loads, both are optimized for max precision of that load. I’m no expert, but that seems like harmonics to me...

 

[Shootin Stuff]

Really? Why? I’ve got a 308 that when zeroed for 168 Amax bullets, shoots Barnes 168 TTX bullets 3” right at 100 yards. It ain’t the wind pushing them there. Both are hand loads, both are optimized for max precision of that load. I’m no expert, but that seems like harmonics to me...

Yep, sure does doesn’t it.

 

[acudaowner]

oh a lighter bullet , i was going to ask cause of all the different 140 gr factory bullets I have tried so far none of them really had that problem elevation yes some slower some much slower than others some faster but none moved left or right solely because of the brand again not that I have noticed .

 

[paulwardd]

This is a pretty common thing to see with different loads. Just the way it goes