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Thread: How close is your trajectory profile?

  1. #1
    Member kimjon's Avatar
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    How close is your trajectory profile?

    To be honest I've never been a good enough shot to really know, but of late I've had access to a farm to do a bit of trial and error testing.

    Up until now I've mainly used a 7stw for long range and it just did what it was told! I must have got lucky as I never had any issues all the way out to 1100. But that's been sold, so I'm using a 7mmwsm, which was fine out to 600, but I knew my velocity values were a bit wrong so error started to show in my predictions (groups were always good but somewhat pointless if not on target), so I put some time aside to fix this.

    Using a G7, and after lots of fiddling in the ballistics program I'm getting about 0.25moa error at 400, bang on at 500, and bang on at 800. This is the best I can get it. I can't stretch it any further safely on this property so beyond 800 is an unknown. Absolutely stoked with my groups, all <0.5moa at all those ranges.

    The weird thing is that the Litz programme recommended using 2940 as my velocity, but that would have had me up to 0.5moa up/down of centre. So I played around and if I use 2970 it gets me within 0.25moa.

    Anyway, how's everyone else finding their predictions, are they one the money...our do you to find a bit of fiddling around is required?

    Kj

  2. #2
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    Sorry, cant help. i had Norm at NZ Hunters team do my head scratching ( yes it cost ) but my come ups are on the money.
    Pity it dosnt always equal results !
    Im not ready to do a writeup of my long weekend Jap hunt yet (still sulking ) but after shooting a small 8pta at 520yds on sat i thought i was the man and then nek minit i videoed myself miss a ripper wall hanger.
    cry,cry,cry,cry,cry,cry,cry,cry,cry,cry,cry

  3. #3
    Member kimjon's Avatar
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    Yup, shootings a confidence game if ever there was one. Some days you're on fire...others you wish you'd just slept in

  4. #4
    Member Micky Duck's Avatar
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    have a go using pointblank on www.huntingnut and see how it compares...I just use the online version but haven't heard any negatives from system at all.

  5. #5
    Member kimjon's Avatar
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    Quote Originally Posted by Micky Duck View Post
    have a go using pointblank on www.huntingnut and see how it compares...I just use the online version but haven't heard any negatives from system at all.
    Cool, thanks for that. I was using shooter and after a bit of playing around I'm getting what I want/need. It's just that for this load its not been as straight forward as it usually is.

    Well try that program and see how it goes. But well continue to use shooter app on my phone now it's pretty much sorted.

    I think two main issues are likely to be my chrony and possibly my range finder. But it doesn't matter now as ling as I only use that range finder, as the load and everything else is all dialed in tune with each other.

    Cheers for letting me know about other app though.

    Kj

  6. #6
    Member kimjon's Avatar
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    Quote Originally Posted by Micky Duck View Post
    have a go using pointblank on www.huntingnut and see how it compares...I just use the online version but haven't heard any negatives from system at all.
    Cool, thanks for that. I was using shooter and after a bit of playing around I'm getting what I want/need. It's just that for this load its not been as straight forward as it usually is.

    Well try that program and see how it goes. But well continue to use shooter app on my phone now it's pretty much sorted.

    I think two main issues are likely to be my chrony and possibly my range finder. But it doesn't matter now as ling as I only use that range finder, as the load and everything else is all dialed in tune with each other.

    Cheers for letting me know about other app though.

    Kj

  7. #7
    Member kimjon's Avatar
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    Just finished watching the applied ballistics dvd, disc three covers exactly this topic. It was awesome, clarified my issues and I'm now very happy with what I did to fiddle my trajectory curve.

    Wish I had watched it a week ago!

    Kj

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    Out of curiosity, did you have to fiddle with the BC to get it to fit?

    To me that would seem the only solution if it's bang on at a couple of ranges but out at others.

    There is a truing function in the app that i've used, but it didn't quite fix a couple of issues I had. Still need to play with it more if I ever get a chance at long range on a nice still day.

  9. #9
    Member kimjon's Avatar
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    Quote Originally Posted by MattyP View Post
    Out of curiosity, did you have to fiddle with the BC to get it to fit?

    To me that would seem the only solution if it's bang on at a couple of ranges but out at others.

    There is a truing function in the app that i've used, but it didn't quite fix a couple of issues I had. Still need to play with it more if I ever get a chance at long range on a nice still day.
    Yeah Ive used that mv calculation tool previously and it worked magic straight away, but on this load it was both high and low which had me buggered.

    So I doubled checked the scope movements, which were verified as a true 1.0moa, so that ruled out the scope.

    The bc was a Litz bc value, so I simply accepted this as true.

    The range...well who knows, but in previous tests my rangefinder is always within a metre or so of everyone elses, so I pretty much acept that as true enough

    The kestrel gives me good atmospheric data, so I accept that.

    That pretty much left mv. The Litz tool helped but I had already stumbled upon a possible solution that gave better results for this range of results (real life test data). Litz mv tool suggested 2940fps, but by upping that to 2970fps which gave me zero error at my longest range, everything else at closer ranges basically fell into line.

    Not sure about longer ranges like 1000y plus, at this stage, will have to verify this later

    Kj

    .

  10. #10
    ebf
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    Quote Originally Posted by kimjon View Post
    Using a G7, and after lots of fiddling in the ballistics program I'm getting about 0.25moa error at 400, bang on at 500, and bang on at 800. This is the best I can get it. I can't stretch it any further safely on this property so beyond 800 is an unknown. Absolutely stoked with my groups, all <0.5moa at all those ranges.
    If you are shooting smaller than 1/2 MOA groups at 400, 500 & 800 you need to come show the guys in the NZ team a couple of tricks...

    Care to post some proof ? It's real easy, take an A3 page. Put 5 dots on it. Shoot 5 shots at each dot. Take a photo and post it...
    Viva la Howa ! R.I.P. Toby
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  11. #11
    Almost literate. veitnamcam's Avatar
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    Why 5 shots? why not 3 or 30?
    "Hunting and fishing" fucking over licenced firearms owners since ages ago.

  12. #12
    ebf
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    OK VC, you can do 30, the rest of us will go for 5

    You know why ... 3-shot group is one thing. Consistently shooting 5-shot groups is exponentially harder. If you really want to see what you can do, shoot 10-shot groups - that seems to be the norm for most recognized forms of "accuracy" competitions - smallbore, NRA fullbore, olympic ISSF etc.
    Viva la Howa ! R.I.P. Toby
    Black rifles matter...

  13. #13
    Almost literate. veitnamcam's Avatar
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    So if ten shot groups is "most recognized" as a test of accuraccy why only shoot 5?
    "Hunting and fishing" fucking over licenced firearms owners since ages ago.

  14. #14
    Member kimjon's Avatar
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    Quote Originally Posted by ebf View Post
    If you are shooting smaller than 1/2 MOA groups at 400, 500 & 800 you need to come show the guys in the NZ team a couple of tricks...

    Care to post some proof ? It's real easy, take an A3 page. Put 5 dots on it. Shoot 5 shots at each dot. Take a photo and post it...
    Im no where near NZ team standard, but I had an exceptional day with zero wind and probably a bit of luck too. I was only doing three shot groups to validate my trajectory, not trying to compete at the Olympics ... but I can hand on heart say my groups were all less that 0.5moa. But I get your point, these would open up the more shots fired for sure.
    veitnamcam likes this.

  15. #15
    By Popular Demand gimp's Avatar
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    Quote Originally Posted by kimjon View Post
    But I get your point, these would open up the more shots fired for sure.
    Would probably change your observed mean point of impact a bit too

 

 

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