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Ballistics program vs Real life
- Thread starter scottyd2506
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scottyd2506
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- Aug 22, 2009
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I'm not sure why a chrono works good at 1st then has 1.5-2% error all a sudden. I assume the sensors have moved apart maybe or angled out some.
Mine is a thick heavy Varmint, over .900 at the muzzle. but I'll mount the magspeed to a platform so I can shoot glock pistols. Thanks for the words of encouragement. want one more now.
cohunt
Well-Known Member
are you using a calculated muzzle velocity? if you use an optical chronograph then you have to calculate your actual muzzle velocity-- you would need to have an exact distance that you set your chronograph EVERY time and small changes in distance from your muzzle, weather and BC will cause errors in MV calculations-- in theory, a magneto spee should give you the closest MV number as its actually measuring at the muzzle, a lab radar can get really close as its extremely accurate but it is still a calculated number --any optical chronograph can have errors from minute sensor movement, light fluctuations, battery level, etc
I find that you can get really close with ballistic apps out to around 4-500 yards, after that all the small errors start to show up and the further the distance, the worse the error factor as everything starts compounding
This is why we should always check dope at the range to verify the actual drop numbers
I find that you can get really close with ballistic apps out to around 4-500 yards, after that all the small errors start to show up and the further the distance, the worse the error factor as everything starts compounding
This is why we should always check dope at the range to verify the actual drop numbers
Canhunter35
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Most likely your chrony
.345 on the 180hybrid on an 1:8 twist works for me to a mile.
As said above, if you're on at a 1000 but off at 600 your g7 is wrong, if you change ur mv and are on at 600 and 1000 then the chrony is lying
.345 on the 180hybrid on an 1:8 twist works for me to a mile.
As said above, if you're on at a 1000 but off at 600 your g7 is wrong, if you change ur mv and are on at 600 and 1000 then the chrony is lying
scottyd2506
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- Aug 22, 2009
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- 159
Still confused by the results, I found one of the problems with my setup.. a lose ring to base screw. Didn't effect groups much, but my zero would change. I think the chrono reading were not off too much..
What really stumps me now is the Velocity variation from my lots of H4831..
Sat I went out, shot some of the new (or old can of H4831) I loaded up w 55.0g H4831.. With 2823 fps set in my program (weather same) I was low at 1k now... I had to set the fps to 2751 fps to get accurate data.
After I shot up those 50, I shot the ones I loaded from another lot I loaded last year. Same charge 55.0g..it was hitting high now.. like 6 clicks.. or 15+ inches at 1000 yards difference. had to enter in 2830-2835 fps to get data corrected.
Wow 70 fps dif..now being it was a change in velocity, the poi at 100-200y could been high, so it may not have been 2835 fps, but I would wager it was at least 50-60 fps or more..
I never stop learning in this LR tuff, and have much more to learn even at my older age. LOL
Anyone else here ever have that much fps swing from powder lots? esp from Hodgdon?
The 1 lb can I got going now seem inbetween the fast and slow one.
I wouldn't say the fast one is fast but "normal".. As almost everyone I see on the net with a 284 and 30 in bbl get around 2820-2840 fps with 55.0g H4831.
I have a new 8 lb container of H4831, so I will load it to around 2820 or so fps at 70-75 temp whatever charge that is. After I'm done with this last 1lb can.
I got a buddy with a wholesales license that can get me a magnetospeed Sporter for $150 when they come in.. So just waiting.
What really stumps me now is the Velocity variation from my lots of H4831..
Sat I went out, shot some of the new (or old can of H4831) I loaded up w 55.0g H4831.. With 2823 fps set in my program (weather same) I was low at 1k now... I had to set the fps to 2751 fps to get accurate data.
After I shot up those 50, I shot the ones I loaded from another lot I loaded last year. Same charge 55.0g..it was hitting high now.. like 6 clicks.. or 15+ inches at 1000 yards difference. had to enter in 2830-2835 fps to get data corrected.
Wow 70 fps dif..now being it was a change in velocity, the poi at 100-200y could been high, so it may not have been 2835 fps, but I would wager it was at least 50-60 fps or more..
I never stop learning in this LR tuff, and have much more to learn even at my older age. LOL
Anyone else here ever have that much fps swing from powder lots? esp from Hodgdon?
The 1 lb can I got going now seem inbetween the fast and slow one.
I wouldn't say the fast one is fast but "normal".. As almost everyone I see on the net with a 284 and 30 in bbl get around 2820-2840 fps with 55.0g H4831.
I have a new 8 lb container of H4831, so I will load it to around 2820 or so fps at 70-75 temp whatever charge that is. After I'm done with this last 1lb can.
I got a buddy with a wholesales license that can get me a magnetospeed Sporter for $150 when they come in.. So just waiting.
