Which powder has the LESS temperature sensitivity?? Varget or RL 15.

10,000+ rounds, Varget has never let me down.

I'll let someone else try RL-15

Both great powders r15 burns little cleaner in my 7mm-08.Almost same FPS in my 7mm-08 with 120 grn BT.

Varget is far more stable than 15.

I also use varget and tested IMR which is supposed to have temperature shift issues. The only time I noticed a shift with IMR is when I purposely cooked the bullet in 98 degree sun for 30 minutes before firing. Next time I tested the load was a 50 degree temperature shift from hot to cold (Texas to Missouri) no noticeable shift at all. So unless you are purposely laying bullets in the sun for an extended time. I think you'll be okay with today's modern powders.

R15 is a double base powder. Double base powders contain more energy than single base powders do. ALL double base powders will be more sensitive to temp variation than a single base powder will. Mfg's who make double base powders try to coat them with chemicals to reduce this.

Double base powders are great because you can get your speeds up, but it comes at a cost. If you are simply loading hunting ammo, the single base/double base argument isn't that big of a deal. If you are trying to make long range shots year round, and want some consistency, then a single base powder is more desirable. One of the most aggressive powders is R17. It is an aggressive double based powder that will show large pressure variation in changes in temperature. If you work up a near max load in the winter time, and shoot that same load in the hot summer, you should expect the round to be a warm or over pressure load.

Also, for my ammunition business, I try to minimize any issues related to temp changes. I use mainly single base powders and the Hodgdon Extreme line of powders, like Varget.

As was pointed out to me elsewhere on this very subject, technology is advancing in smokeless powders. The new Alliant powders are double-base, but are very temperature tolerant. I am speaking of Re16 and Re26. I would assume Re23 is also.

Yes, they have improved quiet a bit. R33 is said to be a newer stable powder that is double based, but it is still showing lots of swing from winter to summer. I know of several shooters who would not dare shoot their winter 28 nosler load in the summer time. They had major pressure issues in warmer temps. So, I don't know exactly which one's to trust.

They're loading them bassackwards then, aren't they? I always do load workup in warmer temps, so cooler temps become a non issue, not vice-versa.

Well, the issue with double based powders, is it changes up your accuracy node with the pressure differences from winter to summer temps. So the guys shooting the 28 Nosler with R33 are using them for hunting only. So they work up the load in winter time, since that is when they will be shooting it. They don't shoot them in the summer. But some have, and had pressure issues. I just can't get on board with the R33 yet.

Never tried R33, but R22 works really well in my 7mags, and R26 works great in my .243.

R22 is temp sensitive. I ran it for years in my 300 WM competition rifle. It's such a great powder and easy to shoot good.

I'm not sure Re33 belongs in the temp tolerant column with 16, 23, and 26. That said, I was advised by a ballistics tech at Western Powders that a powder can show a lot more sensitivity in some cartridges and not so much in others.

Quit posting at work.

At least i work. Besides, i am on break Crawfish.

Somewhat, IME. I've hunted with it in 75deg temps, and 10deg temps and had no change in POI out to 400 yds. Not long range I'll admit.

I have heard about RL 17 temperature sensitivity. I just got back from the hot sun in Namibia and shot RL 17 with no problems. Same max load that I use in the winter. Checked primers and cases for signs of pressure. No sticky bolt lift. Points of impact were same at 100-200 yards.

Well, a "book" max is different than the "actual" max of the round in your rifle. If you pick a max charge from the published reload data, it may not be the actual max pressure of the rifle you are shooting it in. When you shoot this book max load in warmer temps, it's still a safe load and not showing any pressure signs.

Now, if you work up an "actual" max pressure load in your rifle (where you find max pressure and back it down slightly) in the winter time, there's a good chance it will be over max pressure in warmer temps, possibly having sticky bolt lift and wearing out primers. This is the issue with an aggressive double base powder like R17. You will not find me using any R17 in my ammo for this reason. It's too unstable.

What temps are you hunting in?

Normal hunting temps. But what I'm saying is, R17 is too unstable from cold temps to warm temps. If I write 2700 fps on the box, that can easily change depending on the temps. Plus the pressure issues because of the change in temps.

A max load can be an over max load in the summer temps. It causes the ammo to be inconsistent from season to season. It's a great powder if you want top speed in a certain caliber. But that powder charge will generally only work around that temp it was developed in. I need something more stable and consistent, so I use other powders that do not have these temp issues.

I think we're using all kinds of different unstated definitions of "temperature sensitive." I've read many opinions stating the Re22 and/or Re17 are not temperature sensitive, said opinion based on the fact that the poster got his deer (or whatever). My own definition is whether or not the velocity varies significantly when shot at 35 degrees and 95 degrees---for instance. I suppose POI is another way to make up your mind, but in IMO measured velocity is the only way to be sure one way or the other.

I used to use Re22 in .280, and I got some really nice groups with it but I ditched it in favor of H4831. I've also played with Re17 in a few cartridges and found that it was too temperature sensitive to suit ME...and that decision was based on chronographed velocities at different temperatures. I've got six or seven pounds of it sitting here somewhere on my shelves and NO plan to ever use it again---I've sworn it off TWICE now, and I won't fiddle with it again.

I did a load work up for a guy with R17 when it first came out. Like most shooters, they want it going fast and shooting good. It was about early spring when I did the load work, so cooler temps. I worked up the load in small increments, and found a good group. Right after this good group, I found the max pressure for the rifle. Meaning, the next load up I got some sticky bolt lift and pressure signs on the brass. Fast forward to summer time and he's blowing primers, literally popping primers out of the brass on each firing. He called me a told me about it, and I said that load was WAY too hot, and to stop shooting it. He said the speeds were also a lot faster than originally when I shot it.

Why does it do this? It's because R17 is a double based powder and it sensitive to temperature changes. The run of thumb is about 1 fps per 1 degree. I've seen it more, I've seen it less.

1 fps per degree ??

Whaaaat?

I think you might see different ratios, depending on what the temperature actually is. In other words, x fps/degree when comparing the load at 20*F to 60*F, but something greater than x fps/degree from 60* to 100*. A single ratio does not hold true across all temperature ranges.