Ballistic question - I am stumped
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dfanonymous
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Doesn't matter if you have a problem. It's a fact of shooting. The OP is shooting at 600 and 1k. PBR is not the issue, plus it can still be done at 100y. However that's beside the point.
proof:
You'll notice that the numbers match the OP's issue at 600y.
Yet another case of garbage in, and garbage out. Zero matters. It might be just a number, but you are literally dealing with just numbers in this game.
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Main reason you zero 100 is that the effects or weather aka atmospherics are negligible at that range. The further out it you go the more theyre being included into your rifles "true" zero.
Anyways. Back to the OP, in order for me to match your confirmed hits with the data you gave at 400 and 600, I have to drop your MV to 2775 FPS with a G7 of .311. And then run your G7 BC from .311 to .4 to get to your confirmed 1k dope of 20.75.
What optic are you using? And have you checked your tracking?
Anyways. Back to the OP, in order for me to match your confirmed hits with the data you gave at 400 and 600, I have to drop your MV to 2775 FPS with a G7 of .311. And then run your G7 BC from .311 to .4 to get to your confirmed 1k dope of 20.75.
What optic are you using? And have you checked your tracking?
Mikecr
Well-Known Member
#1 We don't know what he's really verifying with his Kestrel, nor how the information is being loaded into software
#2 Everybody confuses air density parameters
#3 You demonstrate your own confusion, while thinking that pressure has anything to do with temperature
#4 You contribute further to #2 with DA (a calculated prediction rather than actual measure)
OP, if you can answer questions in post #6, there is a chance the solution will arise as a simple matter.
Hmm so a rifle zeroed at something other 100 isn't going to work right because of atmosphere?
Some folks that shoot F class keep their guns zeroed at 600 because that's where they shoot most of the time. I'll let them know they're doing it wrong.
Zero where you want and for how you intend to shoot. Always check your zero is correct at another distance farther out and adjust BC etc. I think that the reason most shooters go with 100 is it is the longest range most can check at. I don't have that limitation.
Some folks that shoot F class keep their guns zeroed at 600 because that's where they shoot most of the time. I'll let them know they're doing it wrong.
Zero where you want and for how you intend to shoot. Always check your zero is correct at another distance farther out and adjust BC etc. I think that the reason most shooters go with 100 is it is the longest range most can check at. I don't have that limitation.
Mikecr
Well-Known Member
Need to know what air density conditions where (not just muzzle velocity) when G7 BC was determined.
Otherwise, you do not know, and can't calculate, what local BC will be. It's your baseline which software needs to account for.
Otherwise, you do not know, and can't calculate, what local BC will be. It's your baseline which software needs to account for.
BTW the OP's chosen zero of 255 was what he picked for a reason. His rifle and purpose. He was doing correctly and checking it. He discovered a problem. It is not his Zero. That is just a value in the calculations. Other data matters, scope height, twist, barrel length, atmosphere etc. GIGO.
My point, his zero ain't the problem.
My point, his zero ain't the problem.
I understand that but pva isn't advertising the atmospherics they tested the cayugas at. It just showing that the BC is caluculat s at a specific velocity.The drag coefficient is velocity dependent and that G7 BC of .311 was calculated at a 2775 FPS velocity. The OP's velocity is 3150 FPS. So yeah that's gonna make a big difference .
it is interesting tho, that with the G7 BC of .311, when I adjust his muzzle velocity from 3150 to 2775, the predicted drop AB spits out aligns with the OP's actual confirmed hits at 400 and 600 with a 255 yds zero.
Ill see if I can find some more info on their BC testing
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Although I use a 100 yard zero I agree that is not his problem the software would take that into account and correct for it the problem is bad information has been entered is that simple garbage in garbage out
I just don't understand the problem really,manufacturers want the highest possible BC to attract customers and several manufacturers have been known the stretch the truth in regards to this. with that being said verify what the target tells you make that lineup and move on if you have to adjust the BC to make it work what's the problem as long as everything lines up?If the manufacturers are stretching the truth of the BC or bad information has been entered it still comes back to garbage in garbage out
you know I don't know if they're really "stretching" the truth tho. It's math. They "could" give multiple BC's based on several velocity ranges, like Sierra and Hornady does, or they could give an average BC of the projectile over those velocity ranges, but the BC is a velocity based due to the drag coefficient of that projectile. Seems That they just give the BC based on the higher muzzle velocity at a specific DA. Putting down the BC for the highest velocity isn't necessarily un true
You are correct I guess the information is not untrue ,but it is sort of cherry picking putting the most appealing numbers out for all to see
