They are .75moa out around the mid range targets meaning it has a more pronounced curve than the ballistics programmes are calculating, think the ranges must be out, was using the little leica rangefinder and was hard to keep the dot on the target, should have used my bino range finders, would be 30 yards difference for the worst one to make the adjustments add up, at least that means I only need to re-test a target at that one range and that should tell me
Hori, here are the ranges I had, in Yards, Xs denote the plates
290 x
340 XX
471 XX x
564 XX
690 XXX
720 X
835 XXX
1050 XXX
We only shot at the last two, Norway shot at 690, with my rifles.
I found that speed is the variable I need to change the most to get things to "fit" better.
I usually take a few fps off what my cronie tells me & usually it's pretty close.
My 22-243 data must be bang on as I usually hit first or second everytime with it, the others except the 375 not so much to varing degrees......
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A few things I always check/confirm if things aren't quite working out...
1. reconfirm zero, particularly if you are always shooting X clicks high/low consistantly
2. recheck data input, I once put the scope above bore height in the zero height field. Caused some head scratching after confirming zero... previous load had been spot on... I would check your zero range (as BB said), is it yards or metres, and should it be the other way round?
3. It could be BC related, are you using G1 or G7? Quoted BC's don't work in either my 338 or 7mm, both are pushing the projectiles out faster than the velocity range the BC's generally reflect, so the BC's I have settled on are higher
If it's not a first round hit you need to practice more
HH, I've had this occasionally as well & put it down to ranging errors. The ranges I noted were slightly different to yours.
355yds
476
602
680 (Plate just in from the gateway)
704 (plate in the Gut on the hill)
860
1070
I heard someone say they ranged the longest plates at 1050yd, we had 1070 & that's an extra MOA on for my girl gun.
Shut up, get out & start pushing!
Very interesting you should post this, as i have just been through the same process myself!
I struggled a bit to get my actual drops to match the numbers exactly, I played with 4 different ballistic programs, trajectory validation, BC, FPS, and even steeped BC's.
Lernt heaps about fudging charts and got heaps of advice from people that know their shit, and in the end i realised that what you are trying to achieve with a drop chart is to create numbers that match your ballistic curve as close as possible. You are talking about EXACT points at an EXACT distance, which may be a bit to much to ask for. Should however be possible to match most of them with a singe click out here and there.
Some important things to consider that will effect your numbers, especially at the range you are working to: You have to measure your EXACT scope height above bore, you have to make sure your scope clicks are exactly .25 MOA (if they are in MOA), you have to make sure you are not getting any backlash in your scope while shooting those groups - a good tip is to wind your scope up and down between each shot at the longer ranges, make sure your elevation and air pressure match your sighting in conditions.
I can have a play tonight with the numbers, need elevation, pressure, temp, scope height. Is your Zero EXACT in the bull or is it +- 1/2
As per another thread, this is also one of the reasons where it helps being able to shoot a small group at the longer ranges!
Correction to one of the distances.
Looking at my 602yd plate data shot it looks like we misranged that as I dialed for 600 & then needed to correct down 3/4 Moa for a centre hit which would equate to the dist KG & HH got & tie in nicely with my drop chart. (mystery solved)
Last edited by outdoorlad; 01-03-2012 at 02:31 PM.
Shut up, get out & start pushing!
scope height is 1.92"
pressure 986 hpa
I have reduced speed to 2890fps and can get it within .5moa of the real world figures now which may just be as close as I can get it. It ranges from .1 to .5 MOA low across the given ranges leaving a spread of .4, allowing for shooter error I might just add one click to the zero and should have it pretty close.
off to the range again tomorrow...
What time are you going out to the range?
So 986 was the absolute press for the altitude we were at? That would make it about 730ft above sea level, you've applied that correctly
This is what I did if it helps..
BC 0.550
2920fps
730 ft
29 hg
Scope Height 1.8
340 - 4.25
480 - 8
568 (odd one) - 10.5 (sure that was not 590ish?)
700 - 14.75
850 - 20.25
I'm wodering if it should be 590is I see KG and I both had 564-568 while outdoorlad had 602... that would certainly help explain that one. Will try something at the same range again in weekend if all goes well
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