Powder Temperature Sensitivity

[vintec]

I have found plenty of burn rate charts, but where can I find a chart the sates the temperature sensitivity.

Also, what are the expirences that you guys have with ball powders vs stick powders sensitivity, and or how clean they burn.

Thanks

Vince

[ol mike]

Hodgdon extreme siries powders

Vitv one hundred series

Very generalized answer -too many variables.

[johnnyk]

Vince,
To my knowledge there isn't a chart which list or shows the info you desire. Hodgdon used to show this in their free little load data booklets. It would show the velocities of H4895 Extreme along side IMR4895 and other similar burn rate powders at 30 and 70 degree Fahrenheit. I haven't seen these in awhile, but I haven't been looking. I'd check their website. (www.hodgdon.com)...JohnnyK.

[Slim_T]

I am also interested in this type of information. I shot a practice F-class match today at Quantico MCB. When we started it was 10 degrees F outside and I left my ammo in the truck. I worked the pits in the early hours and didn't shoot until noon. So my ammo was around 20 degrees F (guessing) when I started. At 1000yds I shot cold ammo and I was darn near hitting the ground in front of the target. I adjusted 3 moa from my ballistic table to get x-ring. We had a 20 min cease fire and I left my ammo and rifle in the sun. The rifle felt nice and warm on a cold day and so did the ammo. My first shot after the cease fire was about 10in high. I adjusted down 1 moa and again started hitting x/10 ring. I do not believe that the wind changed or that I changed my shooting position significantly. So..I believe that the ammo warming up in the sun changed my point of impact 10 inches at 1000yards. My ballistics table was for 35F, but what it did not account for was the reduction in velocity due to the powder temp. I changed the ambient temp in my ballistics program to reflect the 15F difference and the drop was only slightly affected (8 inches). I then adjusted my muzzle velocity down until the 1000 yard drop was about what I had experienced at the start of my 1000yard shooting. The velocity change was 50fps reduced.

So..I would like to find out what type of velocity change can occur due to temperature change of the power at the time of ignition.

If I cannot find this type of information I will begin to experiment with warm and cold round over a chronograph.

Slim

[vintec]

I found another post covering this subject, there is some good info on it.
powder temperature sensitivity

I would be intrested in seeing more results and info from some you guys. The more data the better.

[Michael Eichele]

It would be hard to develop a chart since so many variables go into the sensitivity of ANY powder. Things like case capacity, load density, bullet weight and cunstruction over the charge, twist rate in relation to the bullet used, free bore, and of course what spread of temperature youre shooting in.

You will use some powders that are not famous for insensitivity and you might find that in your circumstances the difference with 80 degrees of swing is minimal when another shooter with other circumstances finds a HUGE increase or decrease in velocity. You cannot accuratly predict temperature sensitivity and IMHO too many shooters place too much importance on this. Find a good load, learn how much it increaces and decreaces in a given temp spread and BE HAPPY! None of us should be pushing a load to the max where a few degrees sends the load over the line.

Just my .02 cents

[distantfoe]

I believe temperature sensitivity is also more apparent in overbore calibers.