Forums
New posts
Search forums
What's new
Articles
Latest reviews
Author list
Classifieds
Log in
Register
What's new
Search
Search
Search titles and first posts only
Search titles only
By:
New posts
Search forums
Menu
Log in
Register
Install the app
Install
Forums
Rifles, Reloading, Optics, Equipment
Reloading
Powder Temp Stability Test – 8028XBR, Varget, H4350, RL19, RL26, N560
JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an
alternative browser
.
Reply to thread
Message
<blockquote data-quote="tankgijohn72" data-source="post: 1556864" data-attributes="member: 77441"><p>Velocity readings over various temperatures with different powder/cartridge combinations dont always give you a consistent 0.5fps per degree. I worked for awhile in a ballistic lab, and you have illuminated what is a common misconception. Higher temp does not always mean higher velocity. In my own testing at home I have seen a couple cases where velocity got higher at lower temp with my .270. It is hard to perform at home without a temperature conditioning chamber. But if you had one and could plot MV results from say -20 to 120 degrees in 10 degree increments you can accurately characterize a powder/cartridge/bullet combo. Results are not always linear. Data doesn't lie. </p><p></p><p>*******</p><p></p><p>And now for the weirdest of the results…. VARGET, which actually sped up as it got colder…</p><p></p><p>*****************************************************</p><p></p><p>Powder Type – Varget</p><p>Caliber – 308 Win</p><p>Load Data – 45.0gns, Fed Case, CCI200, 165 Partition</p><p></p><p>Warm Group Temp = 70F</p><p>Warm Group Avg - 2699 fps</p><p>Warm Group SD – 12.9 fps</p><p></p><p>Cold Group Temp = 10F</p><p>Cold Group Avg – 2724 fps</p><p>Cold Group SD – 11.5 fps</p><p></p><p>Temp Difference – 60 Degrees</p><p>Avg Vel Difference – This load was 25 FPS FASTER with a 60 degree Drop in temp.</p><p></p><p></p><p>NOTE: I figured this test could not be right, so I ran it again the next day. Here's that data…</p><p></p><p></p><p>*****************************************************</p><p></p><p>Powder Type – Varget</p><p>Caliber – 308 Win</p><p>Load Data – 45.0gns, Fed Case, CCI200, 165 Partition</p><p></p><p>Warm Group Temp = 70F</p><p>Warm Group Avg - 2696 fps</p><p>Warm Group SD – 8.7 fps</p><p></p><p>Cold Group Temp = 2F</p><p>Cold Group Avg – 2716 fps</p><p>Cold Group SD – 13.5 fps</p><p></p><p>Temp Difference – 68 Degrees</p><p>Avg Vel Difference – This load was 20 FPS FASTER with a 68 degree Drop in temp???</p><p></p><p>NOTE: I don't understand the Varget results. Weird thing is I haven't shot this rifle/ammo for about a year. I had a bunch of round loaded for it that I remember developing in the summer time (so probably 80-90 degrees), and the boxes were labeled as having a velocity of 2660 fps. So I was surprised to see velocities around 2700 fps when I shot the warm group. Then even more surprised with I saw them speed up with single digits temps.</p><p></p><p></p><p>****************</p><p>Summary</p><p>****************</p><p></p><p>I mostly found that H4350 is fairly temp stable in the 0.2-0.4 fps per degree range. I also was pleased to find that RL26 was fairly temp stable. N560 was awful, as was 8028XBR (but I only use this for 223 practice ammo).</p><p></p><p>With regard to Varget getting faster as it gets colder, I am stumped by this. Maybe it has something to do with my specific barrel, or bullet combo. Not sure.</p><p></p><p>Hope the data is helpful to people.</p></blockquote><p>[/QUOTE]</p>
[QUOTE="tankgijohn72, post: 1556864, member: 77441"] Velocity readings over various temperatures with different powder/cartridge combinations dont always give you a consistent 0.5fps per degree. I worked for awhile in a ballistic lab, and you have illuminated what is a common misconception. Higher temp does not always mean higher velocity. In my own testing at home I have seen a couple cases where velocity got higher at lower temp with my .270. It is hard to perform at home without a temperature conditioning chamber. But if you had one and could plot MV results from say -20 to 120 degrees in 10 degree increments you can accurately characterize a powder/cartridge/bullet combo. Results are not always linear. Data doesn't lie. ******* And now for the weirdest of the results…. VARGET, which actually sped up as it got colder… ***************************************************** Powder Type – Varget Caliber – 308 Win Load Data – 45.0gns, Fed Case, CCI200, 165 Partition Warm Group Temp = 70F Warm Group Avg - 2699 fps Warm Group SD – 12.9 fps Cold Group Temp = 10F Cold Group Avg – 2724 fps Cold Group SD – 11.5 fps Temp Difference – 60 Degrees Avg Vel Difference – This load was 25 FPS FASTER with a 60 degree Drop in temp. NOTE: I figured this test could not be right, so I ran it again the next day. Here’s that data… ***************************************************** Powder Type – Varget Caliber – 308 Win Load Data – 45.0gns, Fed Case, CCI200, 165 Partition Warm Group Temp = 70F Warm Group Avg - 2696 fps Warm Group SD – 8.7 fps Cold Group Temp = 2F Cold Group Avg – 2716 fps Cold Group SD – 13.5 fps Temp Difference – 68 Degrees Avg Vel Difference – This load was 20 FPS FASTER with a 68 degree Drop in temp??? NOTE: I don’t understand the Varget results. Weird thing is I haven’t shot this rifle/ammo for about a year. I had a bunch of round loaded for it that I remember developing in the summer time (so probably 80-90 degrees), and the boxes were labeled as having a velocity of 2660 fps. So I was surprised to see velocities around 2700 fps when I shot the warm group. Then even more surprised with I saw them speed up with single digits temps. **************** Summary **************** I mostly found that H4350 is fairly temp stable in the 0.2-0.4 fps per degree range. I also was pleased to find that RL26 was fairly temp stable. N560 was awful, as was 8028XBR (but I only use this for 223 practice ammo). With regard to Varget getting faster as it gets colder, I am stumped by this. Maybe it has something to do with my specific barrel, or bullet combo. Not sure. Hope the data is helpful to people.[/QUOTE] [/QUOTE]
Insert quotes…
Verification
Post reply
Forums
Rifles, Reloading, Optics, Equipment
Reloading
Powder Temp Stability Test – 8028XBR, Varget, H4350, RL19, RL26, N560
Top