I don't know if this has been covered here or not, but I would like to know if WW 760 is temperature sensitive? If this has been covered before, my apologies. I was working up loads this past weekend & found WW 760 to give me excellent results at 51 degrees F. My hunting will take place with temps from 50 down to 0 in the worse case. Will this powder be effected adversely with the cold temps? If so how much effect can I expect? Any info would be appreciated. Thanks
Rich Jake

Rich Jake,
ALL ball powders are sensitive to temps below -30F. They are known to detonate at those very low temps. Most powders (ball powders included) are sensitive to temps above 85F in that the pressure will increase with higher temps. There are a new series of powders in the developement stage (some have been released) that are buffered for better temperate consistancy. If you are shooting in temperatures between 50 and 80 degrees you probably won't notice much difference but lower or higher temps will lower or raise pressures enough that you may notice.

PaulS

I have used a ton of WW760 and H414 its duplicate counterpart at 100 to 120 degree temps both in Texas, Mexico and Africas Sudan without a problem in my 7x57 and 375 H&H...I have not hunted nor do I intend to a -30 degrees below zero with either powder...

Thanks Paul & Ray, LOL I don't plan on hunting at
-30 either! So if I"m understanding Paul correctly as long as I'm between -30 to 85 I should be alright. I'm sure that there will some change in velocity due to the change in temp. I'm just wondering how much it will vary.
Rich Jake

I used W760 7mm-08 loads one year out hunting when the temps dropped down to -35 to -40. I didn't measure the velocity of course, but all my shots were falling way short of where I thought they should be (took me a lttle while to figure this out, I'm not the brightest lamp in the store), indicating to me that there was a substantial velocity loss. Also, they sounded differant, and the recoil felt differant. Very odd indeed. - Dan

[ 03-25-2003, 19:36: Message edited by: dan belisle ]

As a big user of H414, I have shot this powder at-6 degrees with no unusual results. As Atkinson mentioned this is a kissing cousin of W760.

If anyone has a chance to try some real cold weather shooting, I'd like to know the results. Sounds like Dan has some experience with this. I wonder how much extruded would be affected?

This is gonna sound crazy but one of the gun "rags" was testing powder and the effects of cold weather about 6-12 mo's ago in a 22-250. GUESS WHAT--760 actually had more pressure as it got colder. It was the only powder to do so. I do not have the gun magazine around anymore but they were testing loads by shooting in 60 degree weather and then putting shells in coolers with dry ice. I think they thought they were matching the same effect as ammo in -10 degree weather.
This was a little hard to believe but that was what they reported and I do think the guys running the test were pretty experienced reloaders.

I've hunted in weather that was -40 and I would say velocity is down with any powder.Trajectory is altered as Dan has indicated and pressure signs (or lack of them) on the primer suggest pressure is way down.I make a point of trying a couple shots at a target in cold weather just to see where the POI is.Mag primers in 06 sized cases are more consistant than std primers and trajectory is not affected as much. Ball powder seems to be affected the most by cold. Pressures seem to be way down and they burn dirty.Conversely they do not seem to be bothered by higher pressure in hot weather as much as other powders. Ray's comments would support that.

All powders are temp sensitive. I think that WW ball powders got a bad reputation many years ago and have never been able to shed it despite some considerable improvments. I use 760 with confidence, then again Utah isnt known for its sub-zero temps.

Guys
Since I posted this question I found a chart on another site that shows the effects of temperature on velocity & pressure.

Essentually this chart suggests that from 50 F to 0 F you can expect about 50 FPS drop in velocity. The chart claims to be close as far as the change of velocity with the temperature. I assume that some powders maybe affected a little more than others, but this is basically what I was trying to find out. I appreciate all the answers & help.
Rich Jake

I'll just add that the winter I had the problems with 760 was both unusually cold and twenty years ago. I have some new 760 here (I still use it in some calibers, it's a very useful powder), I'll give the new stuff a try, either when we get our annual spring blizzard, or next winter. - Dan

I think rather than a loss of velocity in cold weather being the biggest problem, the worst problem with ball powders is when you develop a load in the winter or early spring and then shoot it in mid summer. That can turn a nice, sedate load into a primer-piercing overload.

Anyone else??

If you find a load in the winter that blows primers in the summer, it was too hot in the first place IMO...

Intelligent reloading voids the problem of pressure sensitive powders..I have done a little chronographing in below zero and really hot weather and all I ever got was less than 50 FPS variation, mostly about 15 to 20 FPS, which is about what I get any way, with any load regardless of the weather..I admit this is not very scientific but this is another problem I don't worry about...As long as one does not try to squeeze that last drop of velocity out of his load, he will be OK....

Although I like H414 and WW760, they are not the cleanest burning powders out there anyway...but they can sure make some calibers like the 06, 7x57, 9.3x62 and 8x57 cook.

At temperatures as low as -35 to -40, it is not only the effect on the powder that causes lower velocities and short shots. The greatly increased air density causes considerably more drag (friction) on the bullets, slowing them much earlier in their flight!

I use W-760 quite a bit. I do most of my load work ups in the summer, which, here in Tucson gets hotter'n hell. (try up to 115 degrees) Any load that has proved safe in the 100 to 105 degree range with W-760 has proven perfectly safe in my rifles at my usual hunting temperatures. (From just below freezing in the morning to about 65-70 degrees by late afternoon.) One of my rifles in .308 Win. will deliver accurate groups only with W-760 and I've tried to get better with close to a dozen powders. It's one very fussy rifle.
W-760 makes my 7x57 Model 70 Featherweight smoke, not only with high velocity but with great accuracy as well.
I like the powder.
Paul B.