Temperature sensitive powders

[Mausermolt]

ive always been partial to IMR powders. seems most places carry everything IMR and ive produced some fine shooting loads with them. ive used Varget in most of my milsurps but sometimes switch back to 4064, depending on availability.
ive never really tried any other powders such as most hodgdon, ramshot, alliant ect.

which powders are the least temperature sensitive and seem to produce the most consistency across most meteorological conditions?

im not looking for a reason to fix something thats not broken...just looking to further my knowledge and for some ideas to tinker with

[Unclenick]

You found it with IMR 4064, IMHO. Not only have generations of match shooters preferred it in the .30 caliber platforms for best accuracy, but when Federal developed the Mk 316 Mod 0 version of M118 LR, they dropped reloader 15, which had produced extra pressure and velocity in high temperatures that threw the sniper come-ups off, and replaced it with IMR 4064.

As to actual powder formulations, the whole Hodgdon Extreme line is made to be temperature insensitive, and that can be a help when you always shoot from a cold barrel. Once a barrel starts to warm up, though, that seems to have more effect than the ambient temperature the powder was in. See this article by Denton Bramwell.

[Hammerhead]

I've often read that nitroglycerine looses it's energy faster in cold weather than nitrocellulose, so single base powders should be more stable in the cold.

Speer has a warning in their reloading manual that double base powders can cause dangerous pressures below -20ºf , which seems to be at odds with my first line. I dunno. Living in a very cold climate I tend to buy single base powders. They tend to burn cleaner and ignite easier.

I know a lot of IMR's pistol and shotgun powders are single base. All of the SR series are IIRC.

Maybe the reason Vihtavuori makes a lot of single base powders is their cold climate in Finland.

[hunter52]

IMR stands for "Improved Military Rifle". This goes back to sometime around WW1.
Single base powders are less temperature sensitive than double base.

[Poindexter]

Among rifle powders I have personally tested Varget in .223Rem, .338Fed and 45-70 down to -42dF/dC and I don't have to adjust the zero on any of those scopes for summertime use. I don't know that I have shot it at temps above +80dF.

Among pistol powders all of Universal Clays, TiteGroup, HS-6 and 777 work great for me from Alaska summertime temps down to -42 degrees.

I was having trouble with H4895 in .338Fed below about -20dF, tried Varget and hadn't had to look any further.

I was not a believer about H-110 for many years. Finally I started keeping ammunition loaded with H-110 in the locking toolbox in my truck bed so it was out in the cold overnight. Then I too started having misfires with H-110 between about +30dF and 0dF.

EDIT: I should add I hear A LOT of really good things about RL-15 in cold weather, but I have never used it myself.

[Mausermolt]

so how can you tell if the powder is single or double base?
and just to make sure i got it correct single base powders are the most stable across temp lines?

[Dan Newberry]

Hodgdon owns the IMR line of powders now. DuPont used to have those powders...

Many powders get an undeserved rep for temp sensitivity, I believe, due to folks using non-optimal powder charges. You can get a non-optimal charge to shoot fine--sometimes it'll shoot lights out--but you're "walking the tightrope to accuracy."

It's best to find a deep accuracy node, and stick with that powder charge. Then you'll have less trouble with POI shifting during temperature changes.

I think the more "temperature stable" a powder is made, the more additives it's going to have, and the less predictable it may be. I have found Varget to work very well in heavy charges, with high load density--but in lower density loads, IMR 4064 kicks its yuppie bottom. And as Uncle Nick alluded to, 4064 behaves pretty well in a wide array of temperatures.

I use W748 with great results in pretty much any bearable outside temperature. It does seem to slow down a bit near and below the freezing mark--but again, if you choose the right powder charge, it's not nearly as quirky as some would suggest.

I'm probably going to remain an "old school" powder guy for some time to come... (and I've decided to let the "hold my beer and watch this" crowd field test these new wonder powders a while longer before I try any of them).

Dan

[Poindexter]

Originally Posted by Dan Newberry

I have found Varget to work very well in heavy charges, with high load density-

I do agree and should have said so. I like Varget best when I am inside published limits but can hear powder grains crunching as the bullet is seated.

[Mausermolt]

ok so let me throw in another bit of info for you.
I use these powders the most:

IMR 4831 in my 300WSM (tack driving load it is)

IMR 4895 in my 30-06, 223 (both produce superb groups in all of my rifles)

IMR 4064 in milsurp rounds: 303 brit, 8mm mauser, 7mm mauser, 6.5 and 7.7 jap,(not milsurp): 348 Win, and tinkered a bit with the 30-06 and the 6mm remington, but the 06' didnt like it as much as 4895. and the 6mm remington got switched o varget because it cut my groups from 7/8" to about 1/3"

and Varget in 6mm remington, 303 brit, 8mm mauser, 7mm mauser, 6.5 and 7.7 jap also

pistol powders im a die hard WIN 231 fan

i havent reloaded for my 30-30 in quite some time...i remember using 4831...but it sucked...any recommendations for that one?

[Dan Newberry]

My favorite 30-30 load is 32.6 grains of RL15, 4064, 748, or Varget with a 170 grain standard bullet for the cartridge. This load will get the best out of your old thutty-thutty as Jack O'Conner affectionately used to call it.

Dan

[Mausermolt]

thank ya Dan
and the rest of you i guess

[Jimro]

Temp sensitivity isn't a linear thing. Powders behave differently with different projectiles in different cartridges.

IMR4064 will have about 20fps difference between 0 and 100 degrees F with a 308 or 30-06 load match load (168 or 175 gr pills). When you get to a much heavier pill in 308, H4350 becomes the clear winner with 5 fps difference. Obviously at hunting ranges the 15fps difference is nothing.

I believe that the key to getting good temp stability is getting a an appropriately high case fill and consistent ignition from the primer. Stick powders have always been known to light easier than ball, so you could use milder primers and get a more consistent initial pressure curve. For Mk316 Mod0 ammo Crane NSWC stopped using arsenal primers and went to a Federal GMM based primer (no word if they thickened the cup for use in semi auto M14/21/25 or M110 rifles).

I have no problem using a heavy charge of ball powder in my AR-15 match loads as I use a milspec primer (plenty hot for cold weather ignition). Obviously a Palma shooter would use a stick powder, and much milder primers.

But between two powders in the same cartridge, you will find some that do a lot better than others. Pretty hard to go wrong with IMR4064, Varget, or H4895 for 308 Win.

Jimro

[Clark]

Kombayotch, now a moderator of Canadian gunnutz, has replicated Hodgdon claims of temperature stability by taking a freezer and an oven to the range.
He heated and cooled the ammo and then measured the velocity of cold and hot ammo.

Me, myself:
I can work up to and get 3228 fps 130 gr 22" barrel 270 with long brass life by using Re17.
I would have bet big money that was not possible.
1) But the temperature variations in Re17 would require such a big safety margin that I would be back down to the performance of many other powders.
2) Further, the temp variations are not good for first shots at long range [hunting, not targets with spotters].

Right now I am a big fan of H4350, because of temp stability.
__________________

[WESHOOT2]

I oft use Magnum primers in loads not specified for temp-related reliable ignition.

Assume nothing; test everything.
I mean, if it matters (like in serious friggin' cold. OR hot, ay?).



"Africa to Alaska, gotta go bang"

[Mausermolt]

Hey man my part of Oregon can range between -20F to 110F. all of my boolits go bang...but if its -20F IM NOT going to be out chasing around a stupid coyote lol

[rebs]

I haven't noticed any change in POI with H335 in temperatures ranging between 30 to 90 degrees.

[Jimro]

Rebs,

Most powders are just fine 0 to 100 F, most of the "hard to ignite in the cold" data comes from military testing across the entire range of expected operational temps (somewhere between -40 and 140 F). Of course a 180 degree swing in temperature will show that all powders are temp sensitive, some just less than others.

And still, some powders are just harder to light off than others, the original BL-C was replaced by BL-C2 when the .gov figured out that it wasn't lighting properly (both standards were for WC846, IIRC, although the later version had a flash suppressant built in along with slightly different burn characteristics).

But the point stands true, that you have to take each powder on its own with each cartridge combination you make to have a valid comparison.

Jimro

[Unclenick]

I thought the military went all the way down to -60°F or -65°F or thereabouts. I always assumed that was for high altitude aircraft, but don't actually know. I've got the primer test specs somewhere, and that may be where I got it from. I'll have to check.

[Jimro]

Unclenick,

They may go down that low, my data comes from an article I read about testing ammo at -40 and finding problems. Whether they go lower or not was not the point of the article. IIRC it was about the original M193 load, and the result wasn't a change in the ammo but tightening the twist rate from 1:14 to 1:12 for Arctic warfare (evidently the ammo was fine but the rifle was lacking).

And I know that the nylon/bismuth "green bullet" was pulled after high temp accuracy went sideways (140 F).

So I know two failure points from ammo trials (where I got the 180 degree swing), but I do not know the upper and lower limits definitively.

Jimro