I am planning on loading 168 grain Nosler BTs for longrange shooting, but do not want to change my load for hunting. Temperaure range could be from -20 to +30. The two powders I am looking at are Varget and R-15. Anyone with experience with either of these in cold weather?
Temperature sensitivity in the .308
- Thread starter Bowie
- Start date
- Location
- Somewhere on the Hudson Bay Coast
I use Varget from time to time in my .308 target rifle, but I'm not sure I have any cold weather chronograph data for that powder. I would count on loosing 100 fps in the cold, but the best bet is to shoot at 3-500 yards and see what your drop is compared to summer time. Last winter I shot some 55 gr BT in my .243 backed with Varget. The warm temperature average velocity is 3965 but at -32 it was 3850.
Both powders have produced great results for me in the 308 Winchester case. Both produced great accuracy, but R15 will get you less pressure and higher velocity (by sometimes as much as 100 FPS), so I really consider it the best of the two (that said, Varget is such a close second, and cheaper to boot, that I shoot Varget almost exclusively these days).
Varget is the only one of the two I've chronographed out of the same gun in both cold and hot weather (-15 to +30). I don't have the exact numbers handy, but I recall that it lost about 80FPS between the temperature extremes -- which was more than I was expecting, given Hodgdon's advertising it as a temp-insensitive powder, but still so small as to make little practical difference in a hunting rifle.
Other side note - those 168 Nosler BT's worked awesome for my wife last year. She shot two deer (one of them a big mature mule deer), both at sub-100 yard range - both of them reacted like they were hit with a truck, and were dead and down within 2 to 3 seconds. I suspect that they'd bet a bit soft of a bullet for an uber-magnum, but in the 308, they are downright awesome on-game performers! My load is 44 grains of Varget, neck sized brass, and CCI primers - gets me about 2720FPS and very nice accuracy.
One other thing worth noting - 150 grain Nosler AccuBond's have shot more accurately than the 168's in both of the 308's in which I tried both bullets. The AccuBond is also a spectacular performer on-game.
Varget is the only one of the two I've chronographed out of the same gun in both cold and hot weather (-15 to +30). I don't have the exact numbers handy, but I recall that it lost about 80FPS between the temperature extremes -- which was more than I was expecting, given Hodgdon's advertising it as a temp-insensitive powder, but still so small as to make little practical difference in a hunting rifle.
Other side note - those 168 Nosler BT's worked awesome for my wife last year. She shot two deer (one of them a big mature mule deer), both at sub-100 yard range - both of them reacted like they were hit with a truck, and were dead and down within 2 to 3 seconds. I suspect that they'd bet a bit soft of a bullet for an uber-magnum, but in the 308, they are downright awesome on-game performers! My load is 44 grains of Varget, neck sized brass, and CCI primers - gets me about 2720FPS and very nice accuracy.
One other thing worth noting - 150 grain Nosler AccuBond's have shot more accurately than the 168's in both of the 308's in which I tried both bullets. The AccuBond is also a spectacular performer on-game.
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RL-15 is one of my favoutite powders, but is a double base. It is much more temperature sensative than Varget.
I suggest varget, with the Winchester standard rifle primer. This will give you less velocity variation than RL-15.
I suggest varget, with the Winchester standard rifle primer. This will give you less velocity variation than RL-15.
Northman999
CGN Ultra frequent flyer
- Location
- Southern Yukon
What I do when winter hunting is keep one "emergency" round in the rifle, and my other cartridges in my inside breast pocket. If you jump something real close, the "emergency" round will do the trick as 80-100 fps velocity loss will not be noticed; if there's more time (almost always is) I can load my nice, warm cartridges from inside my coat and take the shot knowing my loads are behaving exactly like summer. I'm going on a mixed Bison/Wolf hunt in three weeks or so and that's what I'll be doing.
Double base powders are not necessarily more temp sensitive than single base types. All the IMR rifle series are single base, and show temperature sensitivity. Old Norma 205 and the MRP that replaced it are double-base powders and are some of the least temp sensitive powders I have worked with. In my 7x57, the difference in velocity between +27ºC and -30ºC was only 30 fps average. By comparison, H4831SC, an "Extreme" powder, loses 75 fps avg under the same conditions. Reloder 15 is relatively stable through a fair temperature range. Regards, Eagleye
I loaded a batch of 175's back last May and chrono'd them at 2699fps.
I re chrono'd the same batch at the begining of August and they were at 2755fpf.
I did the same with Varget but loaded in July. This load sped at 2594fps.
In August it was 2620fps.
RL15 and Varget are temperature sensitive, just not as most others.
