Velocity variance from what is stated on the box

[BXB77]

I am purchasing a custom turret for a Zeiss V4 on my 6.5 Creedmoor CA Ridgline. I don't own a chronograph, so I did a Trajectory validation at 500 yards and 600 yards. I plug the data into the G7 calculator and it came up 162 fps slower than what is stated on the Hornady box. Is that typical to have that much of a variance? I'm shooting 143 ELDX precision hunter. Box says 2,700, calculator says 2,538. I am shooting right at sea level.

 

[DJL2]

160 fps off would tell me you’re running a barrel that is still breaking in, a bit slow or very short. I get 2650 fps from Hornady’s stuff in a 22 inch 6.5 CM and that is exactly what I would expect from a test velocity taken in a 24 inch tube. That bbl, for example, picked up almost 100 fps from when it was new to 200 rds down it.

That said, two points:
1. Make sure your bbl is fully up to speed.
2. Send in your actual DOPE and have them make the turret accordingly.

You’ve done the work. If you really don’t want to just shoot off your known come ups, have them make the turret according to your DOPE...not a calculation.

ETA: all my shooting lately has been done between sea level and 500 feet ASL, typically somewhere between 50-80 deg F.

 

[Wrench]

sea level sure isn't helping. Have you tall target tested to measure your click values?

 

[16Bore]

Stick with a MOA/MIL turret.

 

[BXB77]

Is it a 20” or 24” barrel?

24"

 

[BXB77]

160 fps off would tell me you’re running a barrel that is still breaking in, a bit slow or very short. I get 2650 fps from Hornady’s stuff in a 22 inch 6.5 CM and that is exactly what I would expect from a test velocity taken in a 24 inch tube. That bbl, for example, picked up almost 100 fps from when it was new to 200 rds down it.

That said, two points:
1. Make sure your bbl is fully up to speed.
2. Send in your actual DOPE and have them make the turret accordingly.

You’ve done the work. If you really don’t want to just shoot off your known come ups, have them make the turret according to your DOPE...not a calculation.

ETA: all my shooting lately has been done between sea level and 500 feet ASL, typically somewhere between 50-80 deg F.

The barrel should be broken in. I have put a couple hundred rounds through it. I would use actual dope, but I don't have a range where I can shoot 50 yrd increments. My range is every 100 yard out to 600 yards.

 

[BXB77]

sea level sure isn't helping. Have you tall target tested to measure your click values?

I haven't, I guess that could be an issue. I'm running a Zeiss V4, it should be pretty accurate.

 

[mxgsfmdpx]

Dont get a custom turret made when you don’t actually know your velocities and velocity spread. Waste of money.

 

[DJL2]

It's worth verifying your optic works as intended. It's also worth begging/borrowing/buying a chrono.

That said, if you define the trajectory at 100, 200, 300, 400, 500 and 600 based on DOPE and the Hornady calculator matches your DOPE, you can use that interpolation from 0-600 yds with high confidence.

 

[fatbacks]

Two recommendations:

Don’t get a custom turret. Print out your dope and tape tape it to your stock. Environmental conditions will never be such that you can be precise In dialing with yardage printed on a turret

If you are going to get it. Run it over a chrono. I think [mention]Unknown Munitions [/mention] has magnetospeeds you can rent.


Sent from my iPhone using Tapatalk

 

[False_Cast]

I’d be verifying that optic’s function before anything else.

 

[Lawnboi]

Just food for thought. Iv had different lots of hornady match ammo that were over 100fps variance, in the same gun.

Just another reason to learn an moa or mil based turret/reticle setup