Thanks for the replies.
I am looking for velocity changes due to cartridge temperature changes. I figured if the action/chamber was hot, it would give me little time to work with, so this would definitely be a "take your time" sort of test. I probably would wait multiple minutes between shots to try to keep the case as cool as possible or at the desired temperature. I don't currently have a temp gun, but that is what I had planned on using to measure the outside case temperature.
I figured that I would seal the rounds waterproof and let them sit in the cooler for 8 hours or so, to insure that the powder, primer, brass case, and bullet were all equally at the same temperature. For the subsequent temperature tests, I figured I would remove a round and let it sit in the shade/sun and slowly start to warm. As the brass came to the next temperature - I would quickly drop it in the chamber and shoot it.
Last night, I purchased a MAGNETOSPEED CHRONOGRAPH V3 KIT (ouch on the price!!) - so it should be easy to have setup and ready to go once each case is at the desired temperature. I planned on using the following measured scale:
- 40o Fahrenheit
- 50o Fahrenheit
- 60o Fahrenheit
- 70o Fahrenheit
- 75o Fahrenheit
- 80o Fahrenheit
- 85o Fahrenheit
- 90o Fahrenheit
- 95o Fahrenheit
- 100o Fahrenheit
I figure, I would shoot three (3) shots at each temperature bracket and record that data. I would average out the MV for each bracket and use that average for all ballistic calculations.
question: Muzzle Velocity changes, by case temperature differences, is not linear - correct?
For if it was linear, I could just do one or two measurements and calculate the chart line. Yet, I figured it wasn't based off of some marketing stuff I have read. I read one gun powder manufacturer state that they try to be more tolerant or less susceptible to Muzzle Velocity changes from a few degree of temperature swings. This made me think it wouldn't be a linear change then, if they could control that?
Ultimately, once I have this information - it should be the final piece of the ballistics puzzle for my rifle. I should be able to enter in the various inputs and accurately project terminus at very long ranges!
BTW, I am doing all this work for my new rifle:
TacOps XRay 51:
Thoughts?
Thanks,
Mike