Conflicting data at different distances... Long range 6.5 Creedmoor

[upSLIDEdown]

So I just finished a new gun. 6.5 Creedmoor. I did an OCW test, and decided to load 41.8gr of H4350 behind my 140gr Berger Hybrids (Hornady brass, BR2 primers). 41.7ish seems to be the perfect pet load for a lot of Creeds, and from what I've seen, most of them are running 2800-2850 out of a 26" tube. Barrel is a 26" Green Mountain blank, 1:8 twist. I know it's not as nice as some high end stuff. It's button rifled, and not hand lapped... So maybe it'll speed up a little after a few hundred rounds, but it still seems slow. Anyway...Here's the issue at hand.

My chrono avg was only 2620.
If I plug that into Strelok+, my data is dead on for longer distances, but not shorter. I shot yesterday and at 910 yds (7.7mils) and 1030 yds (9.4 mils), but at at 450, it says 2.5mils and it took me 2.7mils.

If I drop my velocity in the app down to 2540, it gives me that 2.7mils at 450, but then my 910 yd data goes from 7.7mils (which is dead on) to 8.2mils, and my 1030yd data goes from 9.4 to 10.0. Makes no sense at all. And there's no way it's only going 2540fps.

Anybody got any ideas? Thanks in advance!

 

[Wow]

What is your SD number? How many shots did you use to get your SD?

 

[jamesh]

Sounds like you don't have the correct scope height entered.

 

[upSLIDEdown]

SD? Strelok doesn't have an option for that that I'm aware of, and neither does Shooter that I can see, so I don't think that's an issue.

And I tried changing the scope height in the app, it didn't change anything hardly at all. I also remeasured and it's right. :-\

 

[BCoates]

How many rounds do you have down the new tube? Also, what are the land and groove dimensions? With that load of powder you should be in the mid- to upper 2700 fps. How fresh is your powder and what are you using to weigh it?

On the mil adjustment at 450 yds, you are only talking about a difference of 3" between 2.5 mil and 2.7 mil. A strong headwind can make that much difference. Also, if you don't have the parallax on your scope adjusted correctly, you can be off by that much.

 

[upSLIDEdown]

How many rounds do you have down the new tube? Also, what are the land and groove dimensions? With that load of powder you should be in the mid- to upper 2700 fps. How fresh is your powder and what are you using to weigh it?

On the mil adjustment at 450 yds, you are only talking about a difference of 3" between 2.5 mil and 2.7 mil. A strong headwind can make that much difference. Also, if you don't have the parallax on your scope adjusted correctly, you can be off by that much.

There are only around 150 rounds down the new tube, with a short 20 rd break in, so I'm hoping it gets faster. I have no way to give you land/groove dimensions unfortunately. Parallax should have been dead on, but I guess it's possible. And there was little to no wind that day in any direction, magically enough. I've got a match this weekend so I'll hopefully know more after that. I was just trying to come up with some clarification/ideas on what it could be before then. I may just try to hold top of the target on some of the closer targets in the 4-600yd range in case I see the same thing.

 

[XTR]

You are also assuming that your scope's turrets are accurate, which may or may not be a good assumption.

 

[upSLIDEdown]

You are also assuming that your scope's turrets are accurate, which may or may not be a good assumption.

This is the only logical explanation I can come up with. It's a Vortex Viper PST 6-24x50 FFP. I haven't done a box test or turret tracking test, and won't really have time to before the match I doubt. I'm using a 20moa base, and have the shims in it for the zero stop. I've only got .6mil below zero, but I guess I could still do a box test, just go down .5mils, and go up close to the top and see what happens.

 

[jcampbellsmith]

Try a 'Tall target test' as recommended by Bryan Litz to check out your scope. Regards JCS

 

[BCoates]

You could shoot a group using the reticle hashmarks and then shoot another group using the turret to adjust elevation. Since you have a FFP scope it should be pretty simple.