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Discussion Starter · #1 ·
Just some interesting facts now that I have a chronograph to measure velocity.

125 gr cast, 4.0 HP38, Wolf primer range brass
Springfield XD

Temp 65 F Temp 50

10-05-08 12-08-08
LO 938.6 1039
HI 1004 1090
AVG 977 1064
SP 65.98 51.19
SD 22.64 13.04
PF 121 131


Interesting to note the velocity has increased, Standard Deviation as well as spread has decreased.

Has anyone else experienced this? Is there any straight correlation?

Very informative to see how the reloading manuals mesh with real world measurements.
 

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1. How many shots did you take?
2. What brass did you use was it all one brand and lot?
3. How did you measure the powder in your reloads?
4. Where all the round the same COAL?
5. Was the distance from the chronograph measured and identical for both readings.
 

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Vel. variation w/ temp. is quite common. No direct correlation & varies w/ caliber & powder used. Rule of thumb, work up your loads in higher temps & they will be safe in lwer temps, but not vis versa.
 

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This is not only something that can be proven with the chronograph but something that can be felt also. I have found that the faster the powder, the more the variation, in both rifle and pistol calibers.
 

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Discussion Starter · #5 · (Edited)
Thanks for the reply. I was a little surprised myself to get higher velocities on a colder day then when warmer.

FYI. 10 round strings using a shooting Chrony master.
Same distance between barrel and screens
Brass mixed brands
All loaded on a Lee Progressive press using the Lee powder measure and checked for consistency with a Lyman balance scale
Same setup using the Lee press.

Oh well, the weather here is changing again so I am going to take the opportunity to shoot some more strings and compare results.

I used to shoot Bullseye and Unique when I loaded many years ago. I am having good results with HP38 and I just bought some Titegroup.

Let you know the results.
 

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Thanks for the reply. I was a little surprised myself to get higher velocities on a colder day then when warmer.

FYI. 10 round strings using a shooting Chrony master.
Same distance between barrel and screens
Brass mixed brands
All loaded on a Lee Progressive press using the Lee powder measure and checked for consistency with a Lyman balance scale
Same setup using the Lee press.

Oh well, the weather here is changing again so I am going to take the opportunity to shoot some more strings and compare results.

I used to shoot Bullseye and Unique when I loaded many years ago. I am having good results with HP38 and I just bought some Titegroup.

Let you know the results.
The actual projectile moving through the fluid (in this case air) is also affected by the temperature. I may post some more info on this if anyone is interested in the next week or so. In fact I have a final exam over this topic (and many more :cry:) on Friday.
 
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