Temp stable powder for a 7-08?

[Crazymonkey]

I was out yesterday  shooting  my 7-08 and finally was able to chronograph  my rounds .It's with a magneto speed .What a pain in the butt with a suppressor  on to get it all lined up and reading .But I seem to be shooting  slower than it did in the summer. It shot 3034 in the summer  (lab radar ) verified  Thanks Lance for letting  me shoot for data. Yesterday  it was 2903 the SD was 9 and the es was 22  for the 5 shot string .The group  opened up from all touching to .766 that might be just me .

Load is 45.6gr r17 lapua brass and barns ttsx 140gr with federal 215 primer.

I need to shoot a copper bullet  to hunt California  with my dad till he moves to a free state.

Any powder ideas for my bullet combo.The gun is a interarms action ( mauser) with a brux 26 inch barrel all work was done by Keith at Phoenix  custom rifles. 

[452b264]

            MIN.             MAX. FOR 139/140 GR.BARNES BULLET.   I would use Varget , and all of their load data uses a standard primer (Fed. 210 )

BL-C(2) 39.7 2559 44.1 2854

CFE 223 39.9 2590 44.3 2886

Varget 37.1 2532 41.2 2779

IMR 4064 37.3 2493 41.4 2738

*Big Game 44.2 2664 49.1C 2910

RL 15 38.3 2576 42.5 2817

A-2700 43.7 2661 48.5C 2939

Power Pro 2000MR 41.7 2660 46.4C 2933

RL 17 43.0 2618 47.8C 2911

This is from the Barnes manual for a 120 gr. bullet.

*Varget 39.5 2769 43.9 3052

[L Cazador]

Did you shoot that group that you said was .766" with magnetospeed attached? Also did you deploy a wind flag while shooting group? That's excellent ES and velocity on that load with an excellent group. I wouldn't worry about temperature stability as long as you're within 40 degrees of your actual shooting conditions. If you have to try other powders RL16 and RL23 both have a temp coating as well as Varget. I recently developed some loads with RL17, RL16, and Varget and RL17 won out. My worry about working up a load here and then shooting in California would be the difference in humidity!

[Crazymonkey]

2 minutes ago, L Cazador said:

Did you shoot that group that you said was .766" with magnetospeed attached? Also did you deploy a wind flag while shooting group? That's excellent ES and velocity on that load with an excellent group. I wouldn't worry about temperature stability as long as you're within 40 degrees of your actual shooting conditions. If you have to try other powders RL16 and RL23 both have a temp coating as well as Varget. I recently developed some loads with RL17, RL16, and Varget and RL17 won out. My worry about working up a load here and then shooting in California would be the difference in humidity!

I was shooting  at Rio Salado yesterday  afternoon  .The group  was with the magneto speed attached.I didn't  have anything  to flag wind but could  feel the left to right and would  shoot between  the wind as best I could .I think  I've got the spread figured  out .Measure the two farthest and subtract the Dia of the bullet. Here's  the target. The score keeper logo was to the top.

[MMACFIVE]

2 hours ago, L Cazador said:

Did you shoot that group that you said was .766" with magnetospeed attached? Also did you deploy a wind flag while shooting group? That's excellent ES and velocity on that load with an excellent group. I wouldn't worry about temperature stability as long as you're within 40 degrees of your actual shooting conditions. If you have to try other powders RL16 and RL23 both have a temp coating as well as Varget. I recently developed some loads with RL17, RL16, and Varget and RL17 won out. My worry about working up a load here and then shooting in California would be the difference in humidity!

What is your concern with humidity after they are loaded?

[Crazymonkey]

13 hours ago, MMACFIVE said:

What is your concern with humidity after they are loaded?

Everything  has an effect. My dad use to shoot competition and back in the 70 or 80s  they did a shoot in Mexico  .The loads where made for California  enviroment and when they started shooting  in Mexico  he had issues  with his load and had to figure  it out quickly. Temp,altitude, humidity, and several other things  come into play.I wish I had been around  then to learn it all but my parents  divorced and it wasn't  till I was almost 30 I started  shooting  and hunting  with my dad .

[Hoss50]

If the magnetospeed was attached that could cause the group size change possibly. 

For powder I am going to start working with 6.5 staball in my sons 7mm-08. It is supposed to be less temp sensitive and good in this size case. 

I have a couple pounds of Varget too of the 6.5 staball doesn't work out. 6.5 staball is way easier to find the  Varget though which is why I want to try it first. 

[1uglydude]

I use Varget in 7mm08 pretty much exclusively, and I see no noticeable difference between summer and winter speeds.  Thats the main reason I moved away from RL17...that stuff gave me some crazy velocity swings based on the temperature. 

[Crazymonkey]

I'll see what powder  I can find and try each of them .It seemed crazy to drop over 100 fps from shooting  in the heat to shooting  Saturday  in cooler Temps.

Thanks guys for the information. 

[MMACFIVE]

10 hours ago, Crazymonkey said:

Everything  has an effect. My dad use to shoot competition and back in the 70 or 80s  they did a shoot in Mexico  .The loads where made for California  enviroment and when they started shooting  in Mexico  he had issues  with his load and had to figure  it out quickly. Temp,altitude, humidity, and several other things  come into play.I wish I had been around  then to learn it all but my parents  divorced and it wasn't  till I was almost 30 I started  shooting  and hunting  with my dad .

I agree that everything has an affect. in particular the moisture content of the powder when loaded...the lower the RH the faster the burn speed.

I haven't found any information yet that says the RH changes inside the case after it is loaded though. I seriously doubt outside RH changes can do much to velocities in the short term. I know several times now I've accidently run loaded cartridges through the wash. They have always grouped with unwashed cartridges and the velocities were correct. 

I have seen 100fps velocity difference from one powder lot to another though. I wonder if the first batch was just older and had a lower RH.

 

[Mike S]

These numbers can vary depending on cartridge, but gives some relative comparisons.

https://forum.accurateshooter.com/attachments/temp-burn-chart-png.1191470/

[Crazymonkey]

12 hours ago, MMACFIVE said:

I agree that everything has an affect. in particular the moisture content of the powder when loaded...the lower the RH the faster the burn speed.

I haven't found any information yet that says the RH changes inside the case after it is loaded though. I seriously doubt outside RH changes can do much to velocities in the short term. I know several times now I've accidently run loaded cartridges through the wash. They have always grouped with unwashed cartridges and the velocities were correct. 

I have seen 100fps velocity difference from one powder lot to another though. I wonder if the first batch was just older and had a lower RH.

 

The humidity  has to do with  the drag caused by the change in the air density  .Not so much on what is possibly  going  on inside  the case itself. Just what I started  to read about yesterday  .I didn't  get to read the whole  article. 

[MMACFIVE]

8 hours ago, Crazymonkey said:

The humidity  has to do with  the drag caused by the change in the air density  .Not so much on what is possibly  going  on inside  the case itself. Just what I started  to read about yesterday  .I didn't  get to read the whole  article. 

Could you share the article. 
 

My understanding is RH by itself has a negligible affect on flight. Often RH is conflated with barometric pressure which has a much larger affect.  

 

[Crazymonkey]

Here's  the link to  the article 

url.html

[Crazymonkey]

I'm not  sure it pulled  the link but the article  was by gun digest on the effects of humidity