Labrador vs ballistics chart speeds

[GoosePilot]

Have never used a ballistics program before in this way.

Today I zeroed my z5 by at 200. Shot 100 to 1000 at every 100 interval. Lab radar shots from 500-1000. All shots done over about a 4 hr span. It was 32 when I started and 35 when i finished. Ammo was in garage at 60, then sat outside for 30 min before starting. H1000 on other 50-60 degree days shot 2850fps. Today they started around 2840ish and dropped to 2820ish by the end (as powder cooled off I'm sure). Avg for the 13 rounds recorded was 2830. Shot 24 total. It shot extremely well at all ranges imho.

Question is when i put my data into a half dozen different programs (they were similar) I had to enter 2670fps to get chart numbers to match my recorded turret settings.
It's a z5bt 3.5-18, 20moa rail, low rings. 1.75" above center, 925 ft asl, 34 degree, 29.96, wind at 7 increasing to 12 over 4 hrs at my 6 o'clock
Berger eol 195, g7 .387
300 - 2.5 moa
400 - 5.25
500 - 8.5
600 - 12.5
700 - 15.5
800 - 18.5
900 - 22.75
1000 - 27.75

 

[LongBomber]

Have you ran a tall target test on your scope? One target at 100 yards with an aim point at the bottom, shoot 2 at the aim point, the go up 5moa and shoot 2, keep going up till you reach the top of the target or the moa range you will be using (I like to test 25moa up).

Running at your labradar velocity that is a big drop difference. Unless you are running a slower twist barrel and losing a pile of bc something is out of whack.

 

[dfanonymous]

I would check that muzzle velocity. To get those numbers to match up at each range I've had to do some weird things to the bc and muzzle velocity to even come close to aligning your 100y increment of dope.
Also you talk like a pilot... how are you measuring your atmospherics?

 

[GoosePilot]

Have not done a tall target test. 8 twist 24" proof cf
I am a pilot, have a davis weather station a few miles away.

 

[dfanonymous]

Have not done a tall target test. 8 twist 24" proof cf
I am a pilot, have a davis weather station a few miles away.

Ah. Just realized your user name. I figured when you said asl even though I only heard of msl and agl.

 

[GoosePilot]

Haha. That's just ag pilot slang for Above Sea Level I guess lol

 

[GoosePilot]

Have the runway set up for shooting. Wood stands from 100-400, Steel at 500-1000 and now a mobile 4x4 steel/6x6 wood target

 

[Mikecr]

You have your velocity. Any issues then are not with velocity.
So don't adjust velocity in your ballistic software.
And if you can simply enter your temp, abs pressure, and Rh%, then don't enter altitude. Leave it at zero.

I would also be surprised if your scope adjusts in actual MOA.
Relatively few scopes do, so it's best to test & find out it's actual adjustments, and enter as IPHY per click.

 

[GoosePilot]

I COULD SHOOT OVER A MAGNETO SPEED TO CHECK LABRADAR RESULTS. BASED ON OTHERS RESULTS MY 2850 SHOULD BE ACCURATE THOUGH.

CORRECT IT IS .25"/CLICK. i WAS JUST TRYING TO BE CONSISTENT WITH MY BROTHERS INPUTS IN HIS G7 RANGEFINDER AND I HAVE A MOA TURRET FOR THE SWARO, SO THERE IS SOME "ROUNDING OFF". ITS REALLY THE FIRST TIME I HAVE DONE ALL THIS SO WASN'T SURE WHAT TO EXPECT OR IF I WAS MISSING SOMETHING OBVIOUS.

 

[Mikecr]

You better actually check that .25"/click.. And why would you question your LABRADAR results?
My gut is telling me this is a ballistic software use error. It's just so easy to do.
If your software thinks the G7BC is .387 near freezing temps, that would probably do it.

 

[tdot]

If you have a known metric... ie measured velocity, then I'd not mess with that.

Where did you get your BC for that bullet from? That's the first place I'd look for improvements as almost all other data is measured.

Wind flags down the entire runway? It might be at your 6 at the wind sock/ weather station. But maybe different where you are shooting. Tail wind and head wind can mess with your vertical.

 

[tdot]

And if you can simply enter your temp, abs pressure, and Rh%, then don't enter altitude. Leave it at zero.

Your statement just made me question how I put in data. Why leave Altitude at 0? I had always assumed that this was relating to air density at elevation. But does the temp/pressure/RH% allow the same thing to be calculated?

Would entering the Altitude alter or supersede the info calculated from the other 3 data points? Also do most of my practice at about 50 feet above sea level, so no reason go question.

(I've never looked at these physical equations, so dont fully appreciate how they all interrelate)

I hope that makes sense.

 

[GoosePilot]

You better actually check that .25"/click.. And why would you question your LABRADAR results?
My gut is telling me this is a ballistic software use error. It's just so easy to do.
If your software thinks the G7BC is .387 near freezing temps, that would probably do it.

I HAVE LEARNED TO QUESTION EVERYTHING. ASSUMING SOMETHING IS RIGHT DOESNT ALWAYS WORK SO WELL. MY BROTHER HAS GONE THROUGH THIS A LITTLE MORE THAN ME AND HE SAYS HE HAS HAD TO INCREASE HIS VELOCITY TO MATCH SAY GUNWERKS G7 PROGRAM (OR VORTEX ETC). I HAD TO DECREASE VELOCITY. I GOT THE G7 BC FROM BERGER, THEY HAVE A CHART FOR BC AT VARIOUS SPEEDS AND THIS IS A FAIRLY NEW BULLET SO I FIGURED BC SHOULD BE MORE ACCURATE THAN IN PAST? BUT I AM PRETTY GREEN AT ALL THIS DIALING AND BALLISTIC COMPUTATIONS STUFF.

 

[LongBomber]

The bullet g7 bc is likely pretty close, like not more than .02-.03 off. Berger will have it pretty close, but it will always be slightly different from each rifle.
Lab-radar is also normally pretty close, although you still need to shoot inline with the units field of "vision". And the offset settings will change your speeds 20ish fps.

I would have a serious look at your environmental data and what your scope actually adjusts. A tall turret test is the first thing I do with any scope I am going to dial.