Different loads for summer and winter shoots?

[jimbullet]

I reload 40 S&W using extreme projectiles 180gr and Win231. We usually have shoots in all seasons and all are outdoors. Summers can reach 77 degrees F and winters are about 41 deg F.

 

Is it common to have loads specifically for summer season shooting and loads during winter to meet power factor needed?

 

I ask because I noticed that the load I have been using all summer which was chrono'd appear to have reduced power during shoots in the cold. Is that normal and so do you guys usually work a load for summer and a different recipe for the cold winter shoots?

[Rustygun]

I do not have an answer for you as I load mid range for informal practice, we call it old man IDPA.  Minimal kneeing and running because our outdoor range has very course gravel and we have all had a lot of birthdays.  Due to COVID we have not been able to find a sanctioned competition in this area.  
 

What caught my eye is the minimal temp swing you mentioned.  Where I live (south central US) temps swing from 0 F to 100 F.  Our little group has shot in 20 F and 90-95 F.  Can’t imagine a mild climate like you have.  But I doubt a 30 degree temp swing would have much effect on your reloads.  I will watch to see what the more experienced reloaders here have to say. 

[Sarge]

1 hour ago, jimbullet said:

I reload 40 S&W using extreme projectiles 180gr and Win231. We usually have shoots in all seasons and all are outdoors. Summers can reach 77 degrees F and winters are about 41 deg F.

 

Is it common to have loads specifically for summer season shooting and loads during winter to meet power factor needed?

 

I ask because I noticed that the load I have been using all summer which was chrono'd appear to have reduced power during shoots in the cold. Is that normal and so do you guys usually work a load for summer and a different recipe for the cold winter shoots?

You’ll have to google it. Google will take you to several threads on these very forums. General consensus is it is slower when cold and faster when hot.  Most who compete in both climates typically have two loads or strike a happy medium. 
All you can do is CHRONO hot and cold and see how it goes in your particular gun.

[Yeti]

A 30 degree swing won't have much of an effect on the majority of common powders, but can on some. 

Just compensate for the difference if using powders like WST, TiteGroup, W231/HP-38 or other somewhat temperature sensitive powders.

 

Chrono & load PF for the 41F and you are good to go.

[Banacek]

Don't forget altitude.  When living in Colorado, our loads were fine when chrono-ed, but might not make PF at lower altitude.  

[jimbullet]

4 hours ago, Banacek said:

Don't forget altitude.  When living in Colorado, our loads were fine when chrono-ed, but might not make PF at lower altitude.  

I havent factored altitude.... how big of a difference did you experience?

 

[Banacek]

Enough to up PF by 3 to 5 when traveling out of state.

[jimbullet]

6 hours ago, Yeti said:

A 30 degree swing won't have much of an effect on the majority of common powders, but can on some. 

Just compensate for the difference if using powders like WST, TiteGroup, W231/HP-38 or other somewhat temperature sensitive powders.

 

Chrono & load PF for the 41F and you are good to go.

I wasnt sure if this was a common thing (i.e. have two loads - one for summer and one for winter or otherwise). Getting a feel on what most do?  

 

I'm concerned if I load when its cold and yes make power factor, would that load be dangerous to use when its summer and hot?

 

 

[Farmer]

If your just at minor PF you shouldn’t have a problem. One way to test is to put some rounds in your pocket and some in a ice chest and then run them over a chrono. I had a excellent hunting load for my TC pistol. It was .3 under max and shot great @ 35 degrees but at 70+ it was a little sticky on extraction. Velocity only went up about 40 FPS but psi gained enough that I switched to a different powder. 

[zzt]

On 5/1/2021 at 5:35 PM, jimbullet said:

I'm concerned if I load when its cold and yes make power factor, would that load be dangerous to use when its summer and hot?

 

It depends on the powder used.  With some, yes.  Also, some powders are reverse temperature sensitive.  They get faster as the temps go down.  Some, like WST, are fastest at moderate temps and get slower at higher or lower temps.  You have to chrono.  For my 40sw loads I used Alliant e3.  It has no temp sensitivity.  3.7 under a 180 made 172 PF.  2.8 made 140 for minor.

[thermobollocks]

Load for the worst conditions you expect and don't try to push it closer when you can get away with it.

[RePete]

I run 137/138 PF (9mm) and 170/175 (40S&W and 45ACP) all year round and have never failed chrono anywhere I have been.

[Superkaratemonkeyfighter]

Avoid powders that are temp sensitive or you’ll have to load hot for the worse case senecio. 
but I look at the chrono stages at matches and the killer guys are never are plus 10 over PF. 
optimizing your equipment is important. 
It’s important mentally and physically.