Range Report 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!

 

[Skyking]

Is the bullets bc in app correct?
Is the app scope click value same as scope?
Is you gun zero same as app set zero?
Did you put in the distance your scope is above the center bore of the barrel?
Have you done a box test with your scope?

I would start there.

 

[upSLIDEdown]

Everything is correct in the app. I have not done a box test.

 

[AtOne]

Check your data on JBM - Calculations

 

[tigerfan_9]

everything is NOT right or your data output would be correct......what chrono are you using b/c many output crap. try to shoot at various distances and true your velocity. also try JBM or another app to compare, you many have a setting wrong or the wrong BC causing an issue.

 

[ahhshoot]

Gotta be BC or scope height. Who know for sure though. In the end I've learned that you really need to take that load and that rifle and get your dope the old fashioned way. You will be a lot more confident with it and it will give you real life results in the environment you typically shoot. It can be a pain in the butt to move your target every 100 yards after a couple shots, but it's worth it. Then, cherish that piece of paper or file created with the information therein.

 

[KYpatriot]

If you haven't box tested the scope on a tall target at 100 yards or so start there. You may find that the scope is not tracking like you thnk it is.

 

[tigerfan_9]

Box test the scope then get good data. I have seen first hand 4-5 rifles and many others from those I trust that will rack out past 1000 yards with nothing more then a properly setup ballistic app or AB kestrel using a velocity from a magneto speed chrono. Other chronos are too subjective based on light conditions to give an accurate velocity.

 

[Darkker]

and from what I've seen, most of them are running 2800-2850 out of a 26" tube.

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!

From what I've seen a lot of people also see jesus in their toast.... Unless you are pushing things hard, Creeds aren't generally that fast with Canister powders. While rarely admitted, most barrels are not fast, they are slow.

I don't know anything about Strelok, but as a generality to most free apps I've monkey'd with:
They have rather crappy engines, and don't have updated bullet info. They typically don't account for environmentals, and usually calculate things based on the G1. I find that the G7 is better while super-sonic, but G1 much better once crossing Trans-sonic. Also make sure you have your powder temps, and ES/SD numbers properly entered in the app.

Make SURE: That your scope height is correct and true, your MV is correct: Do a 10-shot average from 20 feet away. Remember also, depending upon where you shoot, that the wind can do all sorts of switching directions on you at that distance. Will really fool with things.

 

[jim_k]

When this happened to me, the box test showed the variable that needed to be changed, and it was the scope click value.
Jim

 

[upSLIDEdown]

Wow, this thread blew up all of a sudden. I think I figured out my issue. I'll hopefully know after this weekend, but I think my zero was .2mils low, and my velocity was about 30 fps low. Fixing both those things would put all the data back on track. I'm hoping this weekend to stretch it way out there and see how it does.

I do have a question though. What do you guys use for your powder temps in the app (Shooter, for instance)? It has a powder temp for when you put in your zero/load info, and then it allows you to Enable powder temp on your enviromentals for the current shooting conditions. Do you guys always keep that enabled? Do you set you original powder temp at whatever the temp was when you zeroed the gun? Just hoping that learning to better utilize an app and having better inputs will result in better outputs.

P.S. Did a tall target test, scope tracks right.

 

[KYpatriot]

The powder temp setting is to correct for velocity variance based on temperature. Your muzzle velocity will vary with temperature because gun powders are more energetic at higher temperatures. Collect muzzle velocity data on cold days and hot days, and use that to calculate how many fps you gain with every degree of temperature rise. You don't have to use this but it is a way to increase the accuracy of your muzzle velocity input.

These apps are very accurate, but are completely dependent on the accuracy of the inputs we give them. Even small errors in sight height, zero, muzzle velocities, BC, density altitude, etc can stack and give us poor results as you saw. Glad you figured it out.

 

[Mod Adahy]

What kind of scope is it? I know you fixed the problem but was just trying to wrap my head around it. Thanks

 

[upSLIDEdown]

Vortex PST 6-24x50 FFP. I did a tall target test and it tracked perfectly. The zero being a hair low was completely my fault though. I plan on trying to get to the next node anyway to see if I can get a little more velocity out of them. Hopefully sometime soon I'll be able to do another OCW test, but I'm hoping to hit another node somewhere around 42.4ish. We'll see.

 

[Aimsmall55]

Are you running the B.C. at the constant (.618)?

Also, I run 42.6 h4350 out of a 27" bartlein GAP Crusader and I'm only at 2820 to 2830 fps. It's the EXACT same speed as the "OLD LOTS of the 140 amax ( factory).

I ran the #'s and something is up. Your 450 yard was on at 2.7 mils. But your 910 yard was 8.2 mils and your 1,030 was 10.1 mils.

I did a numbers test and came up with 2670 fps.

Something is DEFINETLY not right with A) Strelok or B) tracking.

 

[Jedbo]

I do have a question though. What do you guys use for your powder temps in the app (Shooter, for instance)? It has a powder temp for when you put in your zero/load info, and then it allows you to Enable powder temp on your enviromentals for the current shooting conditions. Do you guys always keep that enabled

Your H4350 shouldn't be varying enough to matter. I shoot this powder at matches from 35 degrees to 120 degree and very little change. Humidity and altitude have a bigger effect. I'm in the desert and have found shooting in a high humidity environment and higher elevations has a greater effect than temp and definitely changes my data. When I shoot IMR4350, the temp definitely changes things, but Hodgdon is very stable.