Powder and Temp?

[Out Back]

Was wondering how much Temperature affects the velocity of your load?

If you leave your ammunition out in the Sun and they get hot will your velocity go up above Max Pressure in your rifle.

Like out varmint hunting on a warm sunny day...........

So some powders like Ball powder are really affected by temperature increases? I hear that some powders are not affected by Temperature, not at all? Its not the outside Temperature but the temperature of your ammunition.

I was shooting a load that seemed to work out ok in a 17 Remington but when out shooting Jackrabbits on a warm morning the loads blew some primer pockets I did notice that the ammunition was getting hot...........that was a ball powder called CFE 223

So all powders are temperature sensitive but some are much more??

 

[Dosh]

OB, yes some powders are more sensitive than others. Most powder manufacturer's sites will designate which are less sensitive. I've read prolonged heat can affect powders greatly, rendering cartridges dangerous in some cases. This I witnessed as a friend's young son fired his first round from a 300 magnum and could hardly open the bolt. When questioned, he said he had left the box of ammo in his truck for a year here in AZ. My friend pulled all the bullets and disposed of the powder.

 

[dfanonymous]

Was wondering how much Temperature affects the velocity of your load?

If you leave your ammunition out in the Sun and they get hot will your velocity go up above Max Pressure in your rifle.

Like out varmint hunting on a warm sunny day...........

So some powders like Ball powder are really affected by temperature increases? I hear that some powders are not affected by Temperature, not at all? Its not the outside Temperature but the temperature of your ammunition.

I was shooting a load that seemed to work out ok in a 17 Remington but when out shooting Jackrabbits on a warm morning the loads blew some primer pockets I did notice that the ammunition was getting hot...........that was a ball powder called CFE 223

So all powders are temperature sensitive but some are much more??

yes ammo temp as well as barrel/chamber temp will affect velocity. Also if you are reloading, keep in mind that pressures will also increase as well.
and yes some powders are more resistant to temperature sensitivity than others. Varget for instance is pretty stable for warmer weather, its also a slower burning powering...so keep that in mind as well..
I never max load personally to just to be sure, so i can safely use my load data year round...takes awhile to get load data throughout different seasons..but i use hornady 75gr bthp with 24.7 gr of varget...year round...it works for that rifle both in accuracy and pressure. that just leaves me with truing mv through the seasons, and as bore conditions change, which hasnt been much in my .223

 

[Rich Coyle]

Temp can make a huge difference. A friend and I were rock chuck hunting. The temp was close to 100 degrees in the afternoon. His bolt started getting harder and harder to open. Eventually He couldn't open it at all and had to take the barrel off.

 

[memtb]

Out Back, I do my load development on hot days, preferably above 90 F. I don't want to be surprised with a pressure problem on a hot day. I also try to minimize cartridge heat exposure in a hot vehicle! memtb

 

[nvreloader]

Out Back

Here is the results for my hunting load in my 284 SP Pistol,
my standard load that is safe in this weapon using RL-26 powder
140gr @ 3155 fps = 59057 psi, @ 55*,

Max psi for this case is 63817 psi. (RED LINE)

Same load @ 100* = 65989 Psi, = 3226 fps, (OVER RED LINE)
same load @ 80* = 62993 psi = 3195 fps,
same load @ 60* = 60023 psi = 3162 fps,
same load @ 55* = 59057 psi = 3155 fps, (my hunting load for use during cold weather)
same load @ 40* = 56995 psi = 3123 fps,
same load @ 20* = 54313 psi = 3085 fps,
same load @ 0* = 51834 psi = 3045 fps,
same load @ -10* = 57509 psi = 3026 fps.

As you can see, temps and powders can change for temps being used at etc.
Every powder is different, only with testing can you judge the loads for your rifle etc.

HTH,

Tia,
Don
ps, I sent you a pm.