Getting validation

in Outdoors and more3 years ago (edited)

It sped through the air on the way to the target travelling at 2843 feet per second, well over twice the speed of sound, but slowing as it went...At that speed the distance to the target closes quickly and in only 1.6 seconds it impacted after slowing to only 1487 feet per second...1000 metres away I saw the impact through my scope, and the target drop - It simply collapsed as the imparted energy from the projectile transferred into its head. I felt...Satisfied. The cold bore shot went where I sent it and did it's job. I worked the bolt to reload and settled in to scan for more targets silently satisfied that all the work I'd put in verifying my data was well spent.

[Image removed]

A few days ago I wrote a post about cold bore shift, how to map it and why the data is so important to a long range shooter. It was called cold bore dope and this link will take you to it.

Today I want to talk about the last step for a marksman in gaining confidence in his or her rifle. This step has a few different names but I know it as trajectory validation and it is simply the method in which the ballistics calculator (solver), StrelokPro in my case, is tuned to the rifle, scope and the ammunition - It is essential if a marksman wishes to make cold bore shots and get first-round hits on targets. I'm not talking about shots at close range, I'm talking 800 metres plus and more...Out to over a mile and more where every minute detail matters.

Basically what one does during trajectory validation is ensure that the data in the ballistics calculator is adjusted perfectly to the data that was shot in the field. Below you can see the trajectory page from StrelokPro.

Here you can see the tested muzzle velocity in blue, my shot at 700 metres using 4.7 MRAD of elevation and the calculated muzzle velocity based on that shot. It's different than that as tested and so this data is adjusted in the calculator and is considered validated at 700m. On to 1000m validation. Generally I'd want those two figures, tested and live-fired, to be no further apart than 20 feet per second (fps), but they need to match, and so I adjust the calculator.

Read on for the process.

Trajectory validation - My method

  • Zero the rifle

This may sound like a basic step but it's amazing how many shooters fail to gain a repeatable zero despite it being the platform on which every other factor is built upon. I use a 100 metre zero and at that range I need to be shooting hole-in-hole meaning each round goes in the same hole on the target. I always use top quality scopes so they hold a zero with ease. As stated, the zero needs to be repeatable.

  • Measure muzzle velocity

I use the Labradar doppler radar chronograph to gain this measurement. It measures the speed at which the projectile is travelling as it exits the muzzle. The muzzle velocity (MV) is used to determine the extreme spread (ES) and standard deviation (SD) of the load. I know I say this about every element of long range shooting but, it's critical to know MV. This tested MV is adjusted after the live-fire testing is done to true up the data as I said above.

  • Level the scope

This is a post in itself and I've written about it previously. You can see the post Levelling up, here. Canting a rifle when shooting will send the projectile away from the point of aim - The marksman needs to know the elevation, when dialled, is going directly upwards and if a cant is introduced the elevation will go up and to the left or right, away from the point of aim. The other post explains it pretty well.

The below image is from that post and shows cant in a crude diagram I drew. Read that post for a full understanding.

Scope error shown on right through a canted (right) rifle. Forgive my crude drawing please. 👆

I expend a lot of effort to make sure my scope and scope levels are perfectly level when fitted. Once done it's easy to ensure a level rifle prior to every shot. 👆

  • Ensure an accurate ballistic coefficient (BC) is used

I use the G7 drag model as provided by the projectile manufacturer but the G1 model works ok too, or so I'm told. I'll be honest here and say that I don't play around with the BC too much at all. Some I know will use custom drag curves but I'm a bit of a blunt instrument so I like to keep it simple.

  • Eliminate the variables

This process is all about precision and it makes little sense to attempt do trajectory validation in poor conditions; Too much rides on the data. Wind is the enemy here as it can effect the trajectory left and right and elevation. Crosswinds and swirling winds in gullies and off hills can greatly influence bullet-lift also. So, trajectory validation has to be done in the most favourable conditions, i.e. no wind at all. Not always possible of course, which why it needs to be done well when those conditions exist.

This is also not the time to get creative. Assume a standard prone position and work hard to eliminate any variables the body may introduce...A marksman should be doing this anyway to be honest.

Mirage is another factor to eliminate. In the field it's impossible to avoid and at some stage the shooter will have to shoot through a boiling sight picture. I use the mirage to read the wind speed and direction a lot, but when doing trajectory validation it's the enemy. This is why I always do this process in the early morning or as late in the day as I can, and still actually see. Any time of day with no mirage will work though.

  • Understand the equipment

Taking accurate environmental readings and inputting them correctly into the ballistics calculator is a huge factor. Using cheap sub-standard equipment is not recommended. Making sure the shooter understands the equipment and how each element of data correlates to the other is important. I play around a lot with mine to ensure I understand how it operates. Understanding density altitude, Coriolis, spin-drift, altitude, temperature and humidity and how they all affect the trajectory is very important...As is the correct equipment to measure it. I use Kestrel meters for that purpose and have never been let down. My ballistics calculator is StrelokPro but I used to use Applied Ballistics...I like the more user-friendly nature of StrelokPro though. (Both available on AppStore and PlayStore.)

  • Use the right range

Unfortunately truing drops, trajectory validation, has to be done at a fairly long range as trued data at say, 500 to 600 metres, won't work out further. I start at 700 metres and go out 300 metres at a time out to 1600 metres or beyond. The further the better as I get better data; A little hard work early on will make things much easier later.

  • Be thorough

Taking the time to do this process right, every process around long range shooting really, will pay dividends later. This means working through each step carefully and recording the data; It pays to be meticulous.

Logging all of the shots, recording the environmental situation, the wind call including estimated and the actual wind-correction and elevation adjustment required into a data book is worth the effort. In short, everything needs to be recorded.

For a marksman making that first shot count is important. Hunting at long range, cold bore competition shots or other cold bore shooting is a one-shot opportunity and that shot needs to impact the target...The marksman needs the confidence in the rifle to make it happen and validating the drops, trajectory validation, is how it is done.

Thanks for reading all the way, if indeed you managed it. As always this is not a complete explanation of the process and is not designed to be a manual or training document - Those would be far more complicated. It's just a cut down basic version of the process. Probably it has bored you to sleep, but if you've ever relied on a marksman on overwatch to make a cold bore shot then you'll be glad people know how to do it.

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Be well
Discord: galenkp#9209


So much science behind the pew. Neither the hapless roo nor were prepared for what you sent us today.
Think it really hit home for both of us.

Most get their knowledge body firearms and shooting off the movies I guess; Clearly there's more to it. I do these posts for fun but am glad some get something from them..


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I should send this to my mate. His a farmer and goes out each night hunting boar and foxes. He has an app that connects to his scope which has a camera and can record. He's hit some good shots but misses alot.

Yeah, it might help but without all the equipment and know-how it might not. Farmers are usually very good shooters to a set range, I've rarely seen a bad one, but long range is something completely different. It can be learned though of course.

Would be quite fun, I haven't been shooting in years but not sure anything like this is legal in Aus? I used to go rabbiting with a 12 gage under over. Went roo hunting once with SG Slugs. Damn the kick back in them are intence.

I'm literally partially deaf in one year now from it all. Should have worn ear muffs or something.

not sure anything like this is legal in Aus?

I'm in Australia and do this sort of thing all the time...It's legal.

And yes, you should have worn earpro when shooting...It'll take your hearing away for sure.

Oh yeah. Forgot you were a fellow Aussie!

Born and raised bro. :)

Wow, @galenkp, Can you hit target a kilometer away? It's hard for me to understand your English, but I can see that your guns and scopes are high performance and expensive. 😳
Maybe your hunting gear costs thousands of dollars?

Well, why do you always have a sexy woman with a gun? It seems to be the blonde, glamour beauty that East Asian men imagine.😉

Can you hit prey a kilometer away?

Yes, further than that. Also, prey is not the correct word mate. Use target.

I can see that your guns and scopes are high performance and expensive.

Yes, my scopes are around $4,400-$5,000 AUD each and are all high-end and high performance.

Well, why do you always have a sexy woman with a gun?

That blonde woman in my photos is my wife mate.

Namaste🙏 @galenkp, Nice to see your skills, but here in my are it is banned and not allowed. Thanks for sharing it. Please be safe and take care

Thanks for taking to time to read my post. It's a pity firearms are banned in your area...Although I bet the government have them right?

Good morning @galenkp
I have no clue about guns, equipment, technique of shooting, but I saw your wife and the thought there is a sweet but dangerous angel in that photo! She looks awesome. Cool. 👌

She knows how to shoot too.

I imagined that :)

That's some interesting stuff. I mean seriously even if I never have had use for it.

We didn't have apps and calculators, I started with a slide rule. In HS we had a physics teacher that hunted so part of our deal in the fall was to calculate bullet drops and wind deflection. It may not have helped us much, but you can bet your ass it helped his shooting :)

So. There wasn't a chronograph anywhere in the area so our process was simple. Zero at 100 yards (now I can go either way, then there wasn't a chance :)) Fire 10 at 200 and 300. We relied on bullet mfgs data and on the reloading charts.

Then you estimated the yardage and touched off a round.

I agree that farmers shoot pretty well to a fixed distance, that would be my general data too.

I love these articles about the 'fine points of long distance shooting'. It's really a world I'd never considered but know the process and reasons (slightly).

Thanks mate, I appreciate it. I do those post for fun really, not to teach people anything, but it's cool when someone likes them.

Farmers are really good shooters normally, and make good practical competition shooters too; They're used to shooting in odd positions and in a hurry. Shooting as t range isn't done much though, unless they have a particular interest in it. I've shot against some damned good shooters who are farmers though, that's for sure. Of course, these days and for long distances, all this other stuff is required generally although I'm sure there's people out there who do it differently. I'm just a novice.


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Very nice explanation. I also prefer strelok pro. Looking forward to testing new rifle. Came in Thursday, but apparently the "instant" background checks required here for me to pick up are now taking 2-3 days. Delayed even more from the Xmas holiday. Hoping it will get cleared today. I had quite the challenge replacing the .22-250 that I gave my son. First two choices didn't happen, finally got the third. Quite the long story I'll relate after I get to shoot it once. Ended up with a nice Beretta/Sako model 85 in .22-250 caliber.

Thanks Kris. Yes, StrelokPro is fairly easy to use, so much easier than Applied Ballistics which struggled to run on iPhone when I was using it.

That new rifle sounds nice and 22.250 is a great calibre. I had a Tikka T3 in it, a great varmint gun. I'm looking forward to some posts..

Lol @ instant checks that take days!


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Merry Christmas to you @galenkp 🎅

Of course, I'm happy to do so. 😊

You rock! Looking forward to getting your vote 🙂⏳

Didn’t bore me to sleep, just made me really glad I just show my gunslinger characters in dramatic fashions when they’re sniping as if I had to show all this stuff all I’d be showing was how much I don’t know anything about anything (but Joe I know slightly more than nothing 🤣).

Lol...Yeah it's complicated...Easy once one knows the ways of it, but complicated at the start. I guess I've had years of doing this stuff so it's easy(er) for me...But sit me in front of your rig for instance...Erm...Well, I may know where the start button is! It's all subjective I guess.

I am a bit similar to @bigtom13 in some ways and have never used a scope, could group my shots in a 50 cent circle, used my thumb to judge distance and a wet thumb to judge the wind hahaha.
Yet I received a shooting medal in the army and am just blessed with a good eye.

Let me correct this, never used a scope on a rifle, but used a scope on a fancy cross bow and it's accuracy was simply amazing.

I used a scope-on a .22 caliber squirrel shooter. My 30.06 and .30 .30 were both open. My Dad had a .308 with a 4x scope that I used a couple of times but never even got a shot off with it at anything with legs...

Like I said, I have never used a scope on a rifle Sir Tom, not that I didn't want to, but there was no scope on any of the rifles on the farm.
My cousin has a series of rifles as they hunt far up north, but I haven't fired a rifle since the army in 1972.

Scopeless shooting is possible, but there's limits of course. It's good to know how to do.

Yeah, but it is no match for scope shooting as your proffesional approach is the real way to go.
With a scope there's less chance of wounding an animal and to cause any suffering.

Enjoy the entire post! I'm not this far yet, but I am getting closer. I have my scope leveled, and the level bonded onto the scope so I can verify it's right with a glance.

When I Chronograph my 300 Win Mag, I have to move the chronograph out about 15 feet. If I put it close to the muzzle, it just knocks it over every time I pull the trigger, LOL! There's a little 'breath' on that one....

Do you reload your long distance rounds? I have been buying ballistic points that have a high BC, and have some H-1000 powder that looks good.

I got the ballistic calculator you recommended installed on my tablet, but I am working on the wind velocity first. Don't want to suffer from GIGO, so I'm being careful! After I am better at the wind speed estimate, I may try to make the wind velovity meter talk directly with the tablet.


Thanks mate, there's a lot to it and best to learn little by little, that way it sinks in.

I am eating this elephant one bite at a time, burp! But so far it's pretty tasty, LOL. :-)

I'm trying to make sure that I fully understand each piece so I can use it better. Fortunately I've had a lot of physics classes that helps a lot of this.

Keep your powder dry my friend!


Someone with your level of skills and understanding will pick it all up easily, although taking it step by step is smart.

P.s. I ate an elephant once...It was remarkably tasty.

Ahhh, but did you finish that whole elephant? LOL!

I have to do step by step, because then I understand it and own it....


Well, it came with a side of fries and greens so...Left the greens and concentrated on the fries and elephant! Got through it. 😉

Yeah there's a restaurant close to here that serves game animals. I know they have alligator, Buffalo, emu, ostrich oh, and I think they even serve Roo, LOL! :-)


Haha, it'll be my home away from home when I come to visit!