What makes some powders temp sensitive?

[Desert_Racer]

What makes some powders more temp sensitive than others? I have noticed when opening some cans of powder, that the chemical smell can be overwhelming. For example, a can of RL33 has a much more pungent smell than H1000. Incidentally, H1000 is much more temp stable than RL33.
Is it the chemical content that causes a powder to be more or less stable over a temperature range? Would letting your powder “air out” for a few days and allowing some of the chemicals to evaporate off before loading it help it be more stable?

 

[spife7980]

The particular chemistry is what makes it smell different. If you let it sit out open the humidity will have access to it and that can change its properties. Though some people say that the lot to lot variation is due to different amounts of moisture and letting them sit out can normalize the differences but I’m not sure that’s ever had any substantiation beyond internets tales as far as I’ve seen myself.

 

[Desert_Racer]

A couple local guys, one an old benchrest shooter and the other a PRS competitor, swear by letting your powder air out. They claim more consistency after doing so.

I am going to try it out myself, and see what happens. I live in a very dry climate, so the humidity tainting the powder isn’t of much concern to me.

 

[spife7980]

A couple local guys, one an old benchrest shooter and the other a PRS competitor, swear by letting your powder air out. They claim more consistency after doing so.

I am going to try it out myself, and see what happens. I live in a very dry climate, so the humidity tainting the powder isn’t of much concern to me.

If you’re doing pound jars and not 8 lbers then buy two pounds of the same lot. Leave one closed and air the second. Then once you’ve developed a load with the aired see if the sealed provides equal accuracy and velocity. If they are markedly different then that could be something really interesting.