Temperature sensitive powder

Jrji

Jrji

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I'm looking for a powder to use in cold winter temperatures for my 6.5 Creedmoor loads. I'm finding R-15 is too temperature sensitive. Is Varget a better powder to use in the winter months?
 
Varget should be better

Any of the Hodgdon 'Extreme' powders should be more stable. You lose a little power with the Extreme treatment but gain consistency across temperatures

Fat
 
As previous poster said, most Hodgdon extreme powders are pretty stable, some more than others. I've never loaded 6.5 so I'm not sure on what powders give the ideal burn rate for your bullet weight and barrel length, but I've found in other calibers Varget still gets a little wild in hot temps, while H4350 is very stable. I've also found some of the IMR powders to be very insensitive to temp, 8208 XBR for example is incredibly stable with heavy match bullets in 5.56.

My suggestion is to grab a couple pounds of powder and a chrono and do some testing!
 
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A bit surprising about what it infers for the H4831 and H4831SC. I would have thought they would be pretty much identical considering the only difference is supposed to be the granule length - and there isn't really a lot of difference there if you look at them side by side. One thing about it, the chart confirms what I have found over the years reloading. I like the Hodgdon Extreme powders for their consistency and I have settled on using them exclusively. Sometimes I get to reloading and it takes a while to work through the resulting ammo. Nice that it works pretty much consistently over the variable temperatures through the year.
 
Does any online info tell about performance in canadian temperature extremes. I keep hearing about hodgdon extreme people repeating their marketing hype but i dont know anything about the actual performance difference since i only shoot longer ranges in the winter and my various powders seem to work ok
 
If you use temp sensitive powder, you just need to know your summer and winter zeros. For example IMR4895 has been very accurate for me, but in winter I need to add 0.2mil to my elevation drum ontop of my summer dope.
 
porpoise said:
Does any online info tell about performance in canadian temperature extremes. I keep hearing about hodgdon extreme people repeating their marketing hype but i dont know anything about the actual performance difference since i only shoot longer ranges in the winter and my various powders seem to work ok
Click to expand...

I think whrn I was loading R22 for 7mm I noticed up to 100 fps difference between Aug and Nov.....after seeing that I switched to H1000.
 
Precision rifle blog .com did a test and found that H4350 was the most temperature stable out of the powders they tested which did include varget. 25fps over 115 degrees variance ( Fahrenheit ).
 
I have found H4350 to be great in my 6.5 Creedmoor. I'm still testing bullets and fine tuning loads. I keep the Varget for the .308, 4831SC for my 300WM, and H4895 seems to work the best for my 223. All are bolt guns used at ranges of 300-500m.
 
A buddy of mine is using 42.4grs H4350 under a 143 ELD-X and is getting sub 1/4 moa (custom bolt gun). I'm using 38.1gr Varget under a 129gr SST in my Modern Hunter and getting just a little better than 1moa.

I haven't done enough testing to see how Varget is in winter but I'll get back to testing it again soon.
 
As a side note the U.S. Military with their long range 7.62 sniper ammo went from using RL15 to IMR-4064 because of the temp sensitivity in Iraq and Afghanistan.

I imagine they would have like to use the improved Australian made powders but went with a U.S. owned company.

Cartridge, Caliber 7.62mm, NATO, Ball, Special, M118LR (United States): 175-grain (11.3 g) 7.62×51mm NATO Match-grade round specifically designed for long-range sniping. It uses a 175-grain (11.3 g) Sierra Match King Hollow Point Boat Tail bullet. Produced at Lake City Army Ammunition Plant. The propellant's (Double base RL15) noticeable muzzle flash and temperature sensitivity led to the development of the MK 316 MOD 0 for Special Operations use.

Cartridge, Caliber 7.62mm Special Ball, Long Range, MK 316 MOD 0 (United States): A 175-grain (11.3 g) round specifically designed for long-range sniping consisting of Sierra MatchKing Hollow Point Boat Tail projectiles, Federal Cartridge Company match cartridge cases and Gold Medal Match primers. The Propellant has been verified as IMR 4064 (single base powder, per NSN 1305-01-567-6944 and Federal Cartridge Company Contract/Order Number N0016408DJN28 and has a charge weight per the specs of 41.745-grain (2.7 g).
 
Bottom left of the chart. In general, average feet per second (fps) change per degree Fahrenheit. Warm up a powder and it burns faster, the pressure rises faster, and the bullet goes faster. The smaller that number is the less the change. In my comments about H4831, it shows 0.36 on the chart, so if the cartridge/powder is 10F warmer then the bullet goes 0.36 x 10 = 3.6 fps faster. H4831SC shows 0.08 so the same increase in temp would be 0.08 x 10 = 0.8 fps faster, not as much. Now, some other powders which are of a comparable burn rate like Reloder 19 would have 1.18 x 10 = 11.8 fps increase. If you build ammo and test/set up your optics at 50F, then go out shooting on a hot summer day at 90F, it starts making a really big difference at long range.
 
Thanks guys for the explanation. Dunno if I can trust the chart a 100%, has some contrary information to popular belief eg single based N150 swings more than the double based N550 that's a surprise. I know from experience that Varget has some wild swings with temperatures more so than the chart. I've personally seen with a 18d/F* change 25-40fps difference versus 2.34fps it's suggesting. YMMV I guess.
 
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