Trajectory Validation

Guys, been playing around with my .270 at various ranges. Just been trying to make the trajectory numbers marry up.

So so far I have got my load - 130gr SST, Norma brass, 60gr AR 2213SC. On a hit sunny day it chronied at right on 3000fps. I have it a bang on 100m zero.

Entered all the data into strelok. Took it to 200m. Strelok tells me up .5 MRAD. Fire. POI strikes 3" low if I recall. Anyway I needed .6 to get it bang on. Trajectory val = 2750 fps.

Try at 330m. Up 1.7 MRAD. Using 2750fps. Fire, hit x3. A little high but hard to tell if it's me or what.

Try at 480m. Up 3.5 MRAD. Strikes way high. Guess -.3 MRAD. 4x hits, off to right but fine for height. Trajectory val showing 2872 fps. Sweet.

But then it doesn't marry up at the shorter ranges. Any body see something I'm doing obviously wrong?

Cheers

I'm thinking I may have done something idiotic at 200m which is fracking the whole picture.

Its my understanding you should shoot at 400+ and ideally that + is as far as possible when using the validate function

Scope clicks as marked??

What about zero at 200 and dial from there. I know a mate that had trouble with a 100 yd zero and deer missed because of it.

You know young Toby would have sorted this for you in about three words:wtfsmilie:

I'm not familiar with strelok. What input options other than the obvious does it have? Inclination?

Also, what scope?

Ran into similar problems, Its the bc set velocity back at 3000 if your chronny is legit and manipulate the bc to match actual drop.bc dosnt have much effect short range but makes more and more difference further out.

Try a 130 or 150 meters zero and establish your tables from there. Is your scope height input good?

Check repeat ability of your scope buy shooting a "square box" as well if you can.

If you're dialling for range, I can't see the point dicking around with weird zero ranges - surely it's better to stick with 100m (or 200m, if you're not shooting anything close) and work out your drop chart from there?

At any rate, I agree that the 200m shooting looks like the outlier, but either way you'll probably want to re-do all of your range data.

Confirmation that your scope moves what it says it should on your turrets is a good starting point b4 completely relying on ballistic tables. Set up a grid @ 100 metres (if possible 2 A4 sheets on top of each other or 1 A3 with grid accurately drawn, use full distance top to bottom to minimise errors) and confirm actual movement equals turret markings. If out input correction into ballistic calculator. Cannot remember if Strelok has that function - I am sure it will. Then do your sighting in zero and then your different range confirmations and then adjustments back into your ballistic calculator.

Agree with zimmer. I had a Bushnell that was .30 per click opposed to .25

Does not explain your low MPI at 200 tho.
Is your setup and position exactly the same all the time.
If using rear support for the stock ie a bag of sorts, and if not perfect every time it will explain vertical variations as well.



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Originally Posted by Maca49

You know young Toby would have sorted this for you in about three words:wtfsmilie:

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.270's are shit

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Originally Posted by Proudkiwi

I'm not familiar with strelok. What input options other than the obvious does it have? Inclination?

Also, what scope?

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I'm using strelok pro which is very comprehensive. Has inclination, corealis, weather, very detailed bullet data input etc.

Scope is a vortex pst 4-16 ffp.

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Originally Posted by R93

Agree with zimmer. I had a Bushnell that was .30 per click opposed to .25

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+1

My Bushnell 6500 over-dials about the same distances as you mention. It took me a while to figure it out and get everything sorted. I thought it was my velocity then the projectiles BC but it turned out to be the scope click values. All sorted and verified now! On target out further than I can realistically shoot!

Try this if you like. Zero at 100 m and shoot 3 to verify. Move to 200 keeping zero at 100 and shoot again if space permits go to 250 or 300. Measure the drop at each range from poa and compare these with streloks figures. Sometimes the real world results are different. As others have said checking the scope ajustment is a good idea. I have a weaver that dials .35 instead of one quarter moa and a red dot that does half moa instead one.

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Originally Posted by Pop Shot

+1

My Bushnell 6500 over-dials about the same distances as you mention. It took me a while to figure it out and get everything sorted. I thought it was my velocity then the projectiles BC but it turned out to be the scope click values. All sorted and verified now! On target out further than I can realistically shoot!

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Mine is a 6500 as well. Still have it as it is a reliable scope but use it on my .223 which I rarely dial unless varmiting.

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Originally Posted by R93

Agree with zimmer. I had a Bushnell that was .30 per click opposed to .25

Does not explain your low MPI at 200 tho.
Is your setup and position exactly the same all the time.
If using rear support for the stock ie a bag of sorts, and if not perfect every time it will explain vertical variations as well.



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Not the same. 200m shooting prone off front and rear bag rest. Longer distances front and rear bag over ute bonnet to get high enough above the scrub.

Might need to go back to basics. Test scope tracking. Run loads over chrony again.

Good idea to go back to basics just to confirm stuff.

There is imo however, a position problem and a difference that will cause vertical variations when changing from shooting prone supported and standing supported.

The difference of surface your support is resting on is one thing.
Next is how the rifle is allowed to recoil.
The butt of the rifle is sitting differently in your shoulder between positions. One being more supported than the other.

Recoil is being absorbed through your body differently affecting our POI.
Try and find a way to shoot the same everytime and make a drill out of it.
Talk yourself through every setup and shot and you should see some consistency both on the range and in the field that we all strive to achieve.




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Forget the chrony. I use shooter, but im sure most programmes are the same.

Enter in your data and get the programme to work out your velocities and go from there. You have enough data to do it. If the 200 is an obvious error, leave that data out.

Mill is a mystery to me, I work in moa...but if you get real stuck I could convert it and plug it into shooter if you have no luck.

Kj

The others have a good point though, first validate your scope click values. Doesn't matter what they are, as if known error exists this can be accounted for too.