load development ?

[TrxR]

Will a load developed in cold weather show more pressure signs in hot weather? Im talking below 0 celcius compared to 30 degrees celcius?

Thanks

 

[Andy Legg]

Will a load developed in cold weather show more pressure signs in hot weather? Im talking below 0 celcius compared to 30 degrees celcius?

Thanks

Darn Straight it will!!! Use extreme caution.

Also, A load developed in Hot weather will lose PSI & Velocity in colder temps.

I shot a .308 load in Summer that was Super Sonic at 1000 yards. Tried to shoot the same load this past November & December and the Shot Marker Targets would not pick it up due to going sub just before hitting the target

 

[TrxR]

So in a 308 how many grains should person go down to be safe?

 

[Fliers]

It also depends on the powder. I keep reading the H3450 is 'temp stable', but I don't know how much that really means.

edit: http://bulletin.accurateshooter.com/2016/07/powder-comparison-test-h4350-vs-imr-4451/

 

[ballisticxlr]

That can't be answered without some knowledge about the existing pressure and every gun is a little different.

Do yourself a favor and test it out so you KNOW FOR CERTAIN. Grab a ThermaCare wrap and wrap up 10 rounds in it, let em heat soak in an insulated container for a while while your at the range. They'll get up around 40C or so. I let mine soak for at least 10 minutes while I shoot rounds I've chilled to under ambient. Once they're heat soaked pull them out ONE AT A TIME and fire over your chronograph and check for pressure signs. When you pull them out of the container just stab them into the chamber, point in a safe direction and fire. Don't let the rifle soak the heat out of the round by leaving it in the chamber while you try and nail a bullseye. Just load, shoot, repeat.

If you're loading up to where you're at or near max pressures when it's cold out, I'd drop a full grain or 2 just to start. Testing is the best way to answer your query though.

The fact of the matter is that there's no such thing as truly "temp stable" powder. There are powders that are more or less affected by temperature changes but none I've ever tested were unaffected at all. Some of the really modern powders I've tested showed as little as .5fps/degF, some others around .7-1fps/degF, some around 1.2 or higher. That's all based on charge weights from 32-44gn.

H4350 I've seen around .7fps/degF in my 6XC. YMMV.

 

[TrxR]

The powder im using is varget in lapua cases , Br2 primers and 185 berger jugernaughts with a powerd load of 42.8 and a 5 thou jump.

 

[nso123]

This is one you are going to have to check out through testing. I will say that Varget tends to be one of the most temp stable powders out there. If your load is short of any pressure signs now, you will probably be fine, but if you are on the edge it could always go up in pressure.

 

[K22]

I've experienced pressure surges with ball powders, namely H380 in a 22 250 and H335 in the 223. I experienced these pressure surges hunting ground hogs in 90 degree temperatures especially with H380. With H335 I experienced significant point of impact changes in the summer.

Since I hunt all year ago, varmints in the summer, predators in the winter I switched to 'stick" powders such as H4895 and Varget which minimized the problems but I still have to do some minor point of impact adjustments.

Another approach is to have a rifle (s) / load combo dedicated to winter hunter vs. summer and vice versa. I've experiment with this approach and it works quite well.