Help with velocity numbers

[Roperboy87]

So I have a .25 creed that I did some load work up on. My lab radar shows my average velocity to be 2850 sd is 5.4 es 17 on 10 shots so I put the number in my kestrel at 600 yards kestrel calls for 3.1 mil shoot .3 tenths high. I then end up going down to 2.8 mils, which makes velocity on target 2960. I then move out to thousand and the new numbers call 6.6 miles which I make impact but I am curious as to how the lab radar and target velocity don't match at all, as a matter of fact it 110fps difference. Any help or anyone ever been down this road.

 

[338 dude]

600 or below I would adjust velocity, beyond 600 I would adjust my BC.

 

[biednick]

There's lots of possibilities, but they all boil down to trying to brute force a physics model into being accurate by altering one input. If you're getting accurate results out to whatever range you want to shoot it doesn't matter.

 

[Roperboy87]

There's lots of possibilities, but they all boil down to trying to brute force a physics model into being accurate by altering one input. If you're getting accurate results out to whatever range you want to shoot it doesn't matter.

True statement but this is the first time ever being 110fps different than what the radar showed

 

[Taylorbok]

I'd guess something else is out of wack. Double/ triple check your zero. Is optic height correct? enviros are good?

 

[Roperboy87]

I'd guess something else is out of wack. Double/ triple check your zero. Is optic height correct? enviros are good?

I check my zero after the 600 before I went and shot a 1000yards even threw on a buddy nightforce since I'm running a mark5. Result are the same with both optic. My load is only 40.8 h4350 so nothing hot at all. I even used my buddy Garmin too. I guess I left out I had 2 buddy shoot the gun just to see if maybe it was me be they got the same thing

 

[Taylorbok]

What bullets you shooting?

 

[Roperboy87]

135 Berger hybrid br4 primer

 

[Barrelnut]

Kinda sounds like the advertised BC of the bullet is off. The imprint of the barrels lands can even affect the actual BC. This seems to be why most rifle, bullet and, ballistic solutions need some tuning. I've had a lot of luck with a Creedmoor by shooting at 700 yards, adjusting the velocity in the App to match the clicks needed. Everything else inside 700 yards always seems to work.

 

[Taylorbok]

Kinda sounds like the advertised BC of the bullet is off. The imprint of the barrels lands can even affect the actual BC. This seems to be why most rifle, bullet and, ballistic solutions need some tuning. I've had a lot of luck with a Creedmoor by shooting at 700 yards, adjusting the velocity in the App to match the clicks needed. Everything else inside 700 yards always seems to work.

That'd be a huge BC # increase to make up that difference. Like .6 vs .33

Something is off, or could be stacking of several issues.

Is the target truly at 600 yards?
Is your zero target truly at 100 yards?
Wind and atmosphere was correct?
scope tracking?

 

[Roperboy87]

zero range is true 100 and the target is exactly 601 and the environmental was capture at the time of shooting 600yards if I leave the kestrel at what the velocity record I have to set bc at like .366 and that can't be right so I adjusted the velocity. This is the only rifle I've ever had do this. At first I was like maybe the barrel settling in so I re chrono and same number only got 280 round down it now.

 

[Barrelnut]

What's the barrel twist and what elevation are you shooting from?

 

[Roperboy87]

7.5 twist 26in barrel 990ft above sea level

 

[Taylorbok]

what size of group did you put down at 600?