Ballistic Help

[shannerdrake]

Hoping some of you better than me at this sort of thing can help!

After years of hunting the exact same setup, I finally decided to get a custom turret cut for my scope. It’s a Burris Veracity 3-15x50 on a Weatherby Vanguard 300WM. Load is Barnes factory 165 TTSX. I have chronographed this load a dozen times on multiple occasions and average velocity is 3064.

Gun is dead on at 250. So shoot a nice 5 shot group at 250. All is good. I put the new turret on. Shoot another shot. Confirm it is good.

Move back to 300 yards. According to my turret it is 4 clicks to get me to 300 zero.

I shoot a group. 7 inches high. Conventional wisdom says 4 clicks is 3in at 300 yards.

I for the life of me can’t figure out how after moving back 50 yards AND adding 3in of elevation, I am consistently 7in high?

It was approximately 85, sunny, and low humidity when I shot.

Would welcome any wisdom.

 

[MThuntr]

Custom turret hash marks will be different than standard 1/4 MOA clicks. Not having used that scope nor turret, it would seem that 2 of their "clicks" clicks would be 300 yards. Correct?

Also did you give them information like sight above bore or was it just a standard that the use?

 

[Wind Gypsy]

What was the size of your groups at 250 and 300 yards?

Were you shooting from the same position (I.E. prone on both)?

 

[peterk1234]

Not sure this helps but I provided BC, type of bullet, weight in grains, bullet speed, altitude, avg temp., twist rate (I think), and scope height to Leupold.

The results were exact when compared to my Hornady app and dope card.

 

[Darkside]

You always Zero at 100yds.
Your 7" maybe from 100 to 300.

 

[Forkyfinder]

There should be about 1 moa (4 clicks) for drop with a 250 yard zero with that bullet at that speed. So that seems correct...

My thought is that you should confirm the scope is moving (test it at 100) up 1 moa when you dial it. It could be a turret/tracking issue.

Other thing - parallax could be the source of the problem. Are you adjusting that? Did you shoot a different position when changing ranges?

 

[mevertsen]

Does it say 35 degrees f on the turret?

 

[Don Fischer]

Well now I'm confused! Think I'll simply keep doing what I do and hope it keeps working. I zero about 3" high at 100 yds then shoot different ranges to see where I am. Those turrets like that were made for people that really know how to shoot!

 

[brymoore]

What elevation is your turret yardage marked for? Are you shooting at that elevation?

Wrong elevation would make the turret marks wrong.

 

[turbobrick]

I ran the parameters on your dial through a calculator, 3064fps, 35*, 900ft elevation, 250 yard zero, .442BC. With the 250 yard zero, you're really set up for shooting the gun with a maximum point blank zero. So, really to get to 300 you usually wouldn't dial from zero, since its only 3.4" (just over 1 moa) low from the 250 mark.

My experience with maximum point blank is mixed. I find it tough to shoot good, reliably interpretable groups with hunting rifles at 250 yards. Any slight error in getting that zero, will really throw you off if you want to dial from there. MPBR really shines if you just want to limit your shots to the distances that are +/- 4", so point of aim in this case to maybe 310 yards.

I'm also not sure that the turret is marked right, I'm pretty suspect of the whole thing.

 

[shannerdrake]

Custom turret hash marks will be different than standard 1/4 MOA clicks. Not having used that scope nor turret, it would seem that 2 of their "clicks" clicks would be 300 yards. Correct?

Also did you give them information like sight above bore or was it just a standard that the use?

Yes everything.

Bullet speed. BC. Elevation. Average temp during hunting. Average humidity. Scope height. Bullet weight.

 

[shannerdrake]

Custom turret hash marks will be different than standard 1/4 MOA clicks. Not having used that scope nor turret, it would seem that 2 of their "clicks" clicks would be 300 yards. Correct?

Also did you give them information like sight above bore or was it just a standard that the use?

Yes. It was two has marks (hash marks are 25yd increments). But it was 4 clicks to cover the two hash marks. Naturally the farther out you go, the more space between hash marks so the more clicks as range increases.

 

[shannerdrake]

What was the size of your groups at 250 and 300 yards?

Were you shooting from the same position (I.E. prone on both)?

3ish at 250 and 4ish at 300.

Sitting at a folding bench with a pack in the front and my fist under the rear stock to control up and down. Nothing changed other than 50 more yards and 4 1/4moa clicks

 

[shannerdrake]

Does it say 35 degrees f on the turret?

Yes.

 

[shannerdrake]

You always Zero at 100yds.
Your 7" maybe from 100 to 300.

Not following. It’s zeroed at 250. The mystery is how does it hit 7in higher at 300 than at 250 with 1moa of elevation.

 

[shannerdrake]

What elevation is your turret yardage marked for? Are you shooting at that elevation?

Wrong elevation would make the turret marks wrong.

Yes. Shooting at exact elevation. Although I am shooting at 85 vs 35 degrees. But temp has small impact at 300.

 

[std7mag]

This right here is why I stay away from CDS turrets and use MOA reticles.

Ok, so to the issue at hand.

Barnes factory ammo.
New box/lot #?
Did you confirm the velocity with the ammo you shot with the CDS?

Did you confirm drops at further than the 250 yard zero before you ordered the CDS?

Are you absolutely certain that the bullet is what it's advertised as being?
IE, is it truly a 165gr TTSX?

I ask the questions about the ammo as I've seen different lots have different velocities.
And with the situation of today's components, manufacturers may change powders to what is available to them.
They may also change powders/components due to costs.
If 55.0gr of powder costs X, and another powder is less expensive for them and can be loaded with 54.5gr, over thousands or tens of thousands of cartridges, the financial difference is real.

And lets face it, they are in business to make money.

 

[Wind Gypsy]

Possible culprits:
1. Your scope does not adjust properly. Could be a boogered scope, could be how it’s mounted that binds up the erector.
2. You lost zero moving between the 2 locations. Could be a scope reliability issue. Could be a mounting system reliability issue (are those talley rings and are they tight and not cracked?). Could be an action screw torque or action bedding issue.
3. Something is going on with your shooting and center of group isn't as close as you thought it was.

Your logic is correct in that it appears your POA shifted over 3 MOA and you only adjusted the scope 1 MOA. There are no realistic ballistic explanations i can think of that would create such a discrepancy.

I'd do a tall target test at 100 to check on scope adjustment function if you're sure everything is mounted tight like it should be.

 

[shannerdrake]

This right here is why I stay away from CDS turrets and use MOA reticles.

Ok, so to the issue at hand.

Barnes factory ammo.
New box/lot #?
Did you confirm the velocity with the ammo you shot with the CDS?

Did you confirm drops at further than the 250 yard zero before you ordered the CDS?

Are you absolutely certain that the bullet is what it's advertised as being?
IE, is it truly a 165gr TTSX?

I ask the questions about the ammo as I've seen different lots have different velocities.
And with the situation of today's components, manufacturers may change powders to what is available to them.
They may also change powders/components due to costs.
If 55.0gr of powder costs X, and another powder is less expensive for them and can be loaded with 54.5gr, over thousands or tens of thousands of cartridges, the financial difference is real.

And lets face it, they are in business to make money.

Yes velocity is confirmed and ammo is consistent. I actually bought a case when I landed on this load because of your concerns above. So it’s all from the same lot.

Also I appreciate everyone’s help in trying to problem solve. I do want to point out that ultimately the problem is that I gained 7 inches of elevation by adding 50 yards to the range and 1MOA of elevation. Even a bullet traveling at 5000fps can’t pull that off.

 

[Bambistew]

How high is it at 100 with the 250 zero? How low was it at 300 with the same 250 zero?

Something is wonky for it to print that high with such a small adjustment. Are you sure the scope is parallel to the bore?