Cold temp power factor

[Pickin]

As the season is coming to an end and cold is setting, I want to start stocking up. I will be using 180 grain on top of Sport Pistol.  If I chrono with a colder temp, what will happen when the next season starts and temps warm up?  Do I need to wait?  See if I can use an indoor range?

 

I just started in Major power factor this season an been using factory ammo. I know factory is over power factor and like the STI I just bought.  Continue to use factory loads until temps warm up?

[Sarge]

You have to determine if a given powder is temp sensitive(speeds up with warmer weather) or REVERSE temp sensitive( speeds up with colder weather) . Maybe you can search for it or see if somebody comes along and chimes in. BUT unless I saw overwhelming opinions one way or the other I wouldn’t load a metric ton of it.

  If you have a range that lets you park close to firing line you can put a box of reloads next to a heater vent and grab 10 at a time and chrono quickly. Then chrono some cold ammo. That should give you a rough idea of the direction your powder will go with temp swings.

[zzt]

Sport Pistol is a new powder, so you have to test.  Generally speaking, velocity increases with heat for most powders.  Some, like the Silhouette I use are reverse temp sensitive.  I don't care.  As long as I make 172PF at the Level III matches in the summer, I don't care if it goes up in the Winter.  Alliant e3 is one powder I know has absolutely no temp sensitivity.  That's what I use for 40 major and minor.  WST is an example of a 'strange' powder.  Its lowest velocities are at the very col end and very hot end, and higher in the middle).

[caspian guy]

Assuming a warm day, what I do with any new load/powder I am dealing with is put 10 or more in a zip lock bag in a cooler with ice.  Put 10 of them in the sun on a warm day or some other way of warming them up so they are warm to the touch.  Shoot them over your chrono along with 10 @ ambient temp.  That will give you some idea of what you are dealing with. Like zzt says if it makes pf under the circumstances you shoot in that's what matters