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Altitude Specific Program for FPS
Altitude Specific Program for FPS
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mikecr
18 posts
Oct 19, 2004
4:12 PM
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Yeah, the velocity retained at 1kyd may be higher because of lower air density/drag(also dependant on temps). But velocity at the muzzle will still be the same. So your barrel tune should be good still.
Last Edited by mikecr on Oct 19, 2004 4:13 PM
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dmoran
Charter Member
32 posts
Oct 29, 2004
9:51 AM
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to Dubya and mike,
I have a Effects on Temperature/Velocity Chart. It is to big to paste in a Post.
If you would like a copy of this chart, email me at :
< dmoran AT csicable.net >
Temperature changes velocity alot. Mike I think you should have this information since there is some disagreement there.
Anyone else wanting a copy, email me also.
Happy Shooting
Last Edited by dmoran on Oct 29, 2004 1:00 PM
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mikecr
21 posts
Oct 31, 2004
11:59 AM
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The only thing I can figure, is that y'all are counting powder temps or individual barrel temp effects.
For these I can understand keeping a log for each individual rifle, as no two would react the same. But how would one know what those temps are at any given moment?
I can also picture heavier air(a piston)in the barrel affecting muzzle velocity a very small amount.
My primary program is QuickLoad. Like my others, It doesn't have an input for atmos temp. What are you guy's using that does? If you know of some formula which might calculate this per bore volume, I could sure use it.
Last Edited by mikecr on Oct 31, 2004 12:15 PM
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dmoran
Charter Member
35 posts
Oct 31, 2004
12:16 PM
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I have the fallowing software
-Quick Load; -RCBS; -Sierra;
-Point Blank; -Pact; -JBM;
They all have Temperature Inputs. Not powder or barrel temps. Actual day temperatures !!!!
Here is crony results I have for the exact same load from different days this month:
Load = [ 105-Lapua / 33.5gr N-140 / CCI-450 ]
10-11-04 / 68-deg.
10-shot average velocity = 3061-fps
10-9-04 / 52-deg
10-shot average velocity = 3022-fps
That is a 39-f/s difference for 16-degrees. By the chart, it comes out with in 4-fps. Real close.
Hope this helps....Happy Shooting
Donovan
Last Edited by dmoran on Oct 31, 2004 12:25 PM
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dmoran
Charter Member
37 posts
Oct 31, 2004
5:32 PM
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mikecr,
You must have some other forms of software then I have. Both Quick & RCSBS that I have, are External. Besides that, Velocity is External data. So your velocity is subject to all External Inputs. The only velocity that stays near the same speed is how it is in the barrel. It does not matter what your bullets speed is in your barrel. The instant it travels out of the barrel, it is now subject to external ballistics and external inputs. Cronographs are also External data acquiring units. As are all Reloading manuals I have ever seen.
Easy as I can explain it is: You go shoot your gun at a your local range, and cronograph those shots, with a weather temperature of 70-degrees and you get XXXX-fps. Now the daily weather changes, and it is 65-degrees out, your XXXX-fps changes to YYYY-fps. You will NOT get the same velocity !!!
So now you need to adjust your Input data to correct your velocity so that your Software is computing apples to apples.
Same as when you shoot from your truck at that deer. The velocity is subject to any atmospheric condition changes that the bullet is subject to.
Hense: "Input"
If you want the same velocity in all weather, all your targets/deer will have to be touching the end of the barrel, and in a controlled environment. With a key word here being: "Controlled Environment". 100% exact same conditions as when you established your XXXX-fps.
Sorry, I have never tested Velocity Speeds from a Truck...
Good Luck
Last Edited by dmoran on Nov 01, 2004 12:18 AM
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