Temp sensitive?

[Sockeye66]

Is RE23 a good alternative velocity wise to RE22. I get a significant increase in RE22 from H1000, almost 150 FPS. Almost enough to deal with the temp sensitivity. If RE23 is better, I may have to look into it.
Shane, I only have experience with one rifle using RL23, the rifle is a 24" 6.5x284. I'm getting 2960fps with a 143gr eldx with good accuracy and low es/sd. RL23 performs better in my rifle in both accuracy and velocity than h4831. Only one example but I'm sold on RL23, hope this helps.

 

[Wedgy]

Amazing how JOC killed all that game from sub zero to boiling hot with war surplus 4831 in his 270. chuckle.

Powder company President: " our sales have dropped."
His flunky: "Let's repackage it and claim it's not sensitive to low/high temps"
Pres: "Great and raise the price too"

Ya gotta wonder how we shot down all those enemy planes from -30 F to 120F with those 20MMs stoked w/4831 ?

Run your ballistics with a 50 fps velocity change, in a .270 with a 150 it's ~3" at 600 7 ~11" at 1,000 yards , if that is acceptable to you then don't worry.
SAAMI loads have room but custom loads at a high node will be over pressure in heat if using a heat sensitive powder.

 

[Dean2]

Despite some of the posts on here, there really are differences between temp stable powder and others. Here we shoot from 95 F to -40 F. You can see some pretty loopy things from powder and primers at -40 and even at 0. For instance, I never use CCI 250 in loads over 75 grains because they just aren't hot enough to provide reliable ignition. In many different guns we have got click booms and failure to fires, even though the powder was part burned and clumpy in the cases. Temp stable powder is more difficult to ignite. The big boomers get Fed 215 or Win Mag primers. The Fed 215 was custom developed for Roy Weatherby for the 378 and 460 Bee cartridge due to their very large powder loads.

My suggestion, stick to the temp stable powders, I no longer use RL powders because they tend to be temp sensitive but just as important, the supply is not consistent. We use a lot of Hodgdon powders, develop our loads in the summer, test group them just before hunting season starts and again in the dead of winter. WE rarely have had to tweak them but we also focus on load nodes where a .5-1.5 grain powder difference doesn't make much difference to group size during the initial ladder tests. Temp stable powder, the right COAL and as wide a node near top velocity as you can find are your best bets for avoiding temperature induced POI and consistency issues.

 

[Wedgy]

Here we shoot from 95 F to -40 F.

What the heck are you shooting at -40F ??? And why ? Don't you Canucks use Celsius anyways , are you confusing the two ? LOL
I shot geese in -20F and everyone's autoloaders jammed, benelli, beretta, etc. Apparently you need a lighter spring and different lube. not for me.
I rarely get below freezing here and only at night but it does get over 100F a lot in summer so I stick with Varget, H4350, H1000, and Retumbo which have worked for me.

 

[Dean2]

-40 C and -40 F are the same temperature.

We do a lot of late season elk hunting, Dec and Jan and the Bison season is in Jan or Feb most years so if you want to hunt them, likely going to be pretty chilly out. Feb Caribou hunts in the NWT can get to -60 without the wind chill, now that there be cold in anyone's books, so that is where you really see what works and what doesn't.. You definitely want dry graphite lube and Hoppes 9 cause pretty much anything else will not work.

 

[adk hunter]

WE rarely have had to tweak them but we also focus on load nodes where a .5-1.5 grain powder difference doesn't make much difference to group size during the initial ladder tests. Temp stable powder, the right COAL and as wide a node near top velocity

Makes sense to me... Very good explanation too but dam that's cold for hunting. I have skied at -70 windchill. That was crazy too!!

 

[jrock]

I generally load within 50 fps of max pressure sign. Thus, if a powder isn't stable enough, it will show up in either warm or cold weather (Retumbo for example).
To track and predict the effects of powder sensitivity, I keep track of all my shooting data and specifically run test at 90 deg + and less than 32 deg. I plot this data on a chart and us a linear function to predict expected velocities at different temps. Getting two points of data at least 20 degrees apart gives enough information to predict the high and low temp velocities. I tested and verified this last winter and was within 10 fps of expected velocity on the first try.

 

[Will Gray]

Thinking of temperature. When the barrel is warm (hot maybe) how long do you leave your rounds in the chamber before firing. Just a few seconds will heat the powder significantly. It may be 59F on the bench but it could be 200F in the chamber.

I may be a slow learner but I have found the quickest way to cool the barrel is to open the action and stand the rifle up so the barrel is near vertical: chimney effect from the heated air in and around the barrel rising quickly drawing in cooler air. Much faster cooling than just leaving it horizontal at the shooting position.

 

[J E Custom]

Not only does temp sensitive powder change the elevation/velocity, It changes the tune of the rifle and load combination (Harmonics) and can increase the group diameter. So just because you may have a great load at test time and temperature, doesn't mean it will still be good with a large change in velocity/pressure.

That is why we look for an accuracy Node to get the best accuracy by changing the powder charge.

Something to think about when dismissing the effects of temp changes on ammo.

J E CUSTOM

 

[jrock]

JE,
On that thought, I feel that changing the charge to compensate for the temperature to get the same velocity may even effect accuracy. I can't tell if its a hunch at this time or if I'm paranoid.

 

[J E Custom]

Thinking of temperature. When the barrel is warm (hot maybe) how long do you leave your rounds in the chamber before firing. Just a few seconds will heat the powder significantly. It may be 59F on the bench but it could be 200F in the chamber.

I may be a slow learner but I have found the quickest way to cool the barrel is to open the action and stand the rifle up so the barrel is near vertical: chimney effect from the heated air in and around the barrel rising quickly drawing in cooler air. Much faster cooling than just leaving it horizontal at the shooting position.

Here is something that I found that really helps on hot days (We have plenty of them). I use a small I Phone charger to power mine and it also works great. If I am set up with a chronograph, and don't want to move the rifle it works good and speeds up the cool down time while I am waiting. If I am testing more than one rifle I do just as you and stand the rifles muzzle up with the action open.

Chamber Chiller

Chamber Chiller - the ultimate rifle barrel and chamber cooler. Designed to prolong barrel life and help maintain your rifles accuracy potential.

www.chamberchiller.com

J E CUSTOM

 

[John Klingenberg]

When I was in Texas I never noticed temp sensitive powders because it was hot when I loaded them and hot when I shot them. Now I live up here in the northern wasteland it's a big deal. I used to load and test in winter to shoot in the nice weather. No go. I'd see wild variations with RL powders. I use Varget, 8208 and CFE now. Still have swings but nothing like before.

 

[Mike D Texas]

Temp sensitive powder is effected most @ high temp. Temp swings of 30 or 40 degrees aren't to bad if the low temp starts at 30 degrees and goes to 70 degrees. But 70 to 90 degrees will have a larger effect in only 20 degrees and if you go to 100 degrees. The last 10 degrees can almost double the effect on the powder. In other words the higher the temp the greater the effect.

Loading during the winter months can limit use during the hotter months with some powders. A load that has very little pressure can become dangerously hot in extreme high temps. One of my favorite (Accurate) loads velocity is 3010 ft/sec during hunting season but when the temperature
reaches 90 to 100 degrees, it will soar to 3160. (A 150 ft/sec increase with hard extraction) and I wont shoot that load if the temp is much over 70 degrees.

If I hunt with that rifle during the hotter months, I switch to Varget and avoid the pressure, it doesn't shoot as well (Accurate) but it is close enough.

Sometimes heat sensitive powder just shoots better, but can be managed if you know the temp range it likes.

J E CUSTOM

I agree. Some of the temp stable
powders just leave too much performance on the table.

 

[redneckdan]

Same here, I shoot all winter mostly for practice but there is the occasional coyote or I've been on late season hunts too.

Its was -25F the afternoon this picture was taken, morning temps were lower than -44. My winter load is a 69 SMK over 4064 with a mag primer. 3 season load is 69 smk over 748 with a mag primer.