Help with Ballistic D.O.P.E

Hi Team
Just wondered if there’s a simple fix/solution to the issue I’m having.
Quick run down. Im shooting a 18inch 308 with a Swaro scope using the 3dot coloured dial u system. Ballistic data app I’m using is strelock pro.
I’ve developed a new load and trying to figure out my data.
I have verified my load at 400yards by working backwards in changing velocity to get the correct amount of clicks required at that distance. In theory I thought the rest of my data should line up however when i shot at 500 I was 8 inches low which requires an extra 6clicks.
My question is how do I get my data to line up. Hope someone can understand what I’m trying to get across.
Thanks Matt. .

Best to calibrate that kinda thing at the furthest distance you can, no? The closer you are, the smaller the drops you are working with, and so the more a small bit of noise or error in measuring will screw you up further out.

Check your zero, height over bore, BC, and use the 500m drop to do your reverse calculations from.

Better yet, use a chrono. Must be someone nearby on here who can help you out.

Thanks @Pommy. Was going to be my next step was check against chrono . My data at 500 puts me 3inchs high at 400 so I’m a bit confused as to what step to take next to get it to line up.

What pill is it mate?

Swaro’s Z5s dial 0.975” per 1 MOA. They don’t dial TMOA or IPHY. You need to set up your ballistic app to account for this variance. My profile on my ballistic app is set to IPHY for the dial unit (1.000”) and then you set a correction factor which accounts for the 0.025” difference from the IPHY. Screenshot below should explain hopefully. Once the data entries in your app are all correct then it’s a matter of shooting target at said range and adjusting MV if required in your app to make your solution match your real world results. Shouldn’t be a huge change if you got a reliable MV from a good chronograph and all the data in your app is correct.

Watch some applied ballistics you tube video on truing or validation
Not sure if streloc has validation software.
Fudging stuff is a pretty slow way to do things with dubious results.
AB has comphrensive information and their applied ballistic apps is the best there is.

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Originally Posted by Kelton

What pill is it mate?

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168grain A-Max

@stagstalker thanks for the info Il look more into that. I’ve got mine set on SMOA which I thought accounted for the Swarovski scope not being true MOA.
Cheers @andyanimal31 Il jump on and check some out. Yeah should have started with the chronograph just knew I was close and once I’d shot a group at 400 and 500 I’d be able to work backwards and work it out but not quite lining up like I thought it would.

Also double check your zero, make sure it's bang on what you have input into strelok.

I imagen your some where around 2450-2550? The 16 inch im using the 168 at 2420 and the 18 the 178 at 2477 with 2206h

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Originally Posted by mattstr

@stagstalker thanks for the info Il look more into that. I’ve got mine set on SMOA which I thought accounted for the Swarovski scope not being true MOA.
Cheers @andyanimal31 Il jump on and check some out. Yeah should have started with the chronograph just knew I was close and once I’d shot a group at 400 and 500 I’d be able to work backwards and work it out but not quite lining up like I thought it would.

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Yep found a utube video for strelok pro doing trajectory validation.
Make sure your zero is perfect before you start

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Originally Posted by mattstr

@stagstalker thanks for the info Il look more into that. I’ve got mine set on SMOA which I thought accounted for the Swarovski scope not being true MOA.
Cheers @andyanimal31 Il jump on and check some out. Yeah should have started with the chronograph just knew I was close and once I’d shot a group at 400 and 500 I’d be able to work backwards and work it out but not quite lining up like I thought it would.

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SMOA is the same as IPHY. Shooters MOA / Inch Per Hundred Yards (1.000” at 100 yards). There is still the 0.025” variance when you set your app to that. Been through this with all my Z5s.

Did you confirm zero at the same time you shot 400 and 500?
Did you shoot 400 and 500 on the same day?
Did you account for aerodynamic jump?
How many shots did you use to zero, at 400, and at 500?

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Originally Posted by mattstr

Hi Team
Just wondered if there’s a simple fix/solution to the issue I’m having.
Quick run down. Im shooting a 18inch 308 with a Swaro scope using the 3dot coloured dial u system. Ballistic data app I’m using is strelock pro.
I’ve developed a new load and trying to figure out my data.
I have verified my load at 400yards by working backwards in changing velocity to get the correct amount of clicks required at that distance. In theory I thought the rest of my data should line up however when i shot at 500 I was 8 inches low which requires an extra 6clicks.
My question is how do I get my data to line up. Hope someone can understand what I’m trying to get across.
Thanks Matt. .

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Greetings Matt,
The first step is to chronograph your load. Otherwise it is the old garbage in garbage out. PM me if you need help with chronographing.
GPM.

@stagstalker thanks I will have a look in strelock and see how I can adjust this. Sounds like I need to take a step back and chrono load first of all then go from there. Appreciate the offer @grandpamac I have one that I will be able to use. @Magnetite I shot a tight 5shot group at 100 group so was happy sight in hight was bang on. I shot 400/500 on the same day. I shot 4shot groups at 400/500. I shot a 1.3inch group at 400 and then a 2.5inch group at 500 so was pretty confident of the height adjustment. I corrected via strelock then send another couple at 500 at clay targets to confirm the clicks I had adjusted was correct. sAttachment 222510

Try using the Swarovski ballistic app online. also things like the sight height above the bore measurement is critical.

You don't need a chronograph unless you are doing load development.
Just watch that video and it will become clear!

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I've had a look at strelok. the 0.975 moa that the Swaro dials equals .24375 of an inch at 100 yards. This can be entered into Strelok up to 3 digits, so 0.244. The actual difference at the terminal end is very small out to 500m and would not account for the discrepancy you experienced. So when you say you worked backwards from 400 yards, do you mean you used the Trajectory validation function in Strelok? If you use this it should give you a pretty accurate velocity. After that double check your input. Projectile BC, Sight height above the bore. As I said earlier you should also log into and use the Swaro ballistic app, it is great for setting up the distances for the coloured dots on the scope. I have a Z5 3.5-18 x 44 and always use both apps, they complement each other.

@zeropac any chance you could send a screen shot of where I can enter the scope correction into strelock.
Correct verified at 400 through strelock for velocity.
The following day managed to shoot 400 and 500 however was 8 inches low at 500.
I have since watched the video @andyanimal31 and using my 500yard data verified by bc and it’s put my 400 yard very close. I will check a few different ranges and make sure everything else now lines up.
Thanks for everyone’s input. I have teed up a chronograph so be interesting to compare to now what strelock has come up with.

Here you go, Change the values under scope click unitsAttachment 222716
I agree with Andyanimal. You don't have to have a Chronograph to setup your scope. How about you PM me with all the input details and I will see what data I get out of Strelok and the Swarovski app.

It could be not enough shots to find the true centre. Hornady (podcast ep. 50) did some testing and found five shot groups averaged +/-0.3" away from the true centre at 100yd. A chronograph will let you know if your velocity calculation is sane without a whole lot of rounds.

Cheers @Magnetite have actauly listened to that podcast. The way they want you to sight in is with a whole box of projectiles haha. I have now managed to get all my data to line up thanks .
Thanks for the offer @zeropak with the comments I’ve managed to figure out a couple small things which is now lined up all my data. I will check a couple of different ranges just to be sure but my 500 and 400 line up so in theory all the rest should now be good.

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Originally Posted by mattstr

Cheers @Magnetite have actauly listened to that podcast. The way they want you to sight in is with a whole box of projectiles haha. I have now managed to get all my data to line up thanks .
Thanks for the offer @zeropak with the comments I’ve managed to figure out a couple small things which is now lined up all my data. I will check a couple of different ranges just to be sure but my 500 and 400 line up so in theory all the rest should now be good.

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Excellent. Good to hear.

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Originally Posted by mattstr

I’ve managed to figure out a couple small things which is now lined up all my data.

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Do tell...

I verified the bc in strelock like said in the comments also changed the scope data as discussed. This matched up the amount of clicks at 500 to the correct amount of clicks at 400 ��. I am yet to shoot at shorter distances to make sure that all in between is correct.
So thanks to everyone for the help much appreciated. Might be time to concider an MOA turret .