Post your personal data showing rifle powder velocity vs. temp sensitivity testing.

[MCMXI]

I've made no secret of the fact that I worked at Remington for two years developing ammunition. Pressure and velocity testing was performed at -20°F, ambient (about 70°F) and +150°F for all ammunition and one "blip" at hot or cold during a DV test (design validation test) out of thousands of rounds shot would send us back to the drawing board. All powders are temperature sensitive to some degree or another, and as you can imagine, we were always looking for powders that didn't show pressure spikes hot and cold. We tested many, many powders across numerous cartridges, calibers and bullet weights but that data is proprietary and can't be shown here. In addition, we had state of the art equipment that gave us a high confidence in the data and worked closely with chemists from companies such as St. Marks to tweak certain recipes.

Some people like to regurgitate what they've read on other forums and pass it off as their own knowledge or data. What I'm hoping is that some members here have actually done their own testing and would be willing to share the results. I will admit that all of my testing was carried out while I was getting paid by Remington. I live in a state where temperatures can vary from -40°F to +100°F and shoot all year round. In terms of accuracy I've not noticed a temperature issue shooting 6.5 Creedmoor, .308 Win, .300 Win Mag or .338 Lapua Mag out to 1,050 yards but that may be unique to how and where I shoot, the powders/primers I use, the load density etc.

If you're willing to provide data, I would ask that you show as much as possible to provide a complete picture of the test method, load data, rifle, weather, shooting position, brand of chronograph, calibration etc.

Thanks for your consideration.

 

[Nature Boy]

Sounds like fun. I'm in

 

[Nature Boy]

Here's what I'm thinking my protocol will be regarding this exercise:

1. Load two groups of 20 each .308 rounds with Varget and RL15. All other load variables the same.

2. Shoot 10 rounds each of the Varget and RL15 groups
A. Starting with clean bore, shoot 3 foulers
B. Measure barrel temp ahead of chamber using IR thermometer for baseline
C. Shoot one round each in round robin fashion, spacing shots ~90 sec apart
D. Record chrono data
E. Chamber each subsequent round after previous shot, record barrel temp.

3. Allow barrel to cool to ambient temp and repeat test with remaining 20 rounds.

Chambering the subsequent round quickly after the previous shot should allow for some heat soak to take affect.

Shooting round robin should allow normal distribution of the affect across both groups.

What do you think? What other factors should I consider?

 

[[email protected]]

Not scientific at all, but I did some testing with surplus WC844 powder is 223 rem. The basis of my tests was how extreme cold effected velocity using this powder with standard and mag primers. I loaded five rounds each for four test groups. Two groups were the control group. They were loaded with standard and mag primers and left at room temperature. The next two were also loaded with standard and mag primers, but I placed them in a freezer for several hours.
I fired the first two groups (control) and noted a slightly higher velocity with mag primers over standard. Next up was the chilled group and things got difficult. I had a hang fire which resulted it the death of my chronograph (RIP). I pulled the trigger and click, I held t on target for what seemed like a couple of seconds and began to lower the rifle. Then boom and the round went the my chroney. The remaining four of this group had similar results. I couldn't check the velocity of the group loaded with mag primers, but I noted that they seemed a little off.

 

[Nature Boy]

That's great. What were the results?