Random 8
Member
I often like to test my ammo in extreme temperatures. I have access to some of the coldest weather in the CONUS combined with a place to shoot, so cold is easy. I've fired my handloads to temperatures of -42F. Over the years, I've noticed some interesting (bad) things.
Most notably was with H BL-C2 in an M1 Garand. Following Hornady load data for the M1 with a 168HPBT, I was able to induce, and repeat, what I believe was a flashover detonation event at temperatures below zero. Cases showed minor pressure signs with a load that should have been in the 45Kpsi range. The most notable effect was a bent op-rod, so something weird was definately happening with the pressure curve.
Shotgun ammo has been another problem area. I've had frequent bloopers, or noticeably underpowered shots with both reloads and factory ammo. Faster burning powders seem to be a somewhat suitable remedy for this. My best luck with extreme cold shotgun ammo has been with old fashioned nitro card loads combined with faster flake type powders.
With many of the old standard extruded rifle powders such as IMR 4064 and 4350, I've had no apparent issues, although I suspect a chronograph or 300m target would show some deviance from more standard conditions. Surprisingly, my pest control load for the cabin 30-06 of 14 grains Unique pushing a 110 gr carbine bullet shows no noticeable difference from 90F through -30F.
With handgun loads, I haven't been able to induce any serious malfunctions, but noticeably dirty burning and decreased accuracy with cast bullets and increased leading have been apparent. Seems the cold does something to cast bullet lubes. Coated were even worse. I fired a number of coated (ACME) bullets last winter at temps around -15F. I recovered the bullets from a snowbank in the spring, and it appeared the coating had flat flaked off. Predictably a seriously leaded bore after some 30 rounds was the result, this with a moderate load in 9mm.
Has anybody else explored performance at extremes of temperature? Especially interested in chronograph results (do those even work at 20 below?).
Most notably was with H BL-C2 in an M1 Garand. Following Hornady load data for the M1 with a 168HPBT, I was able to induce, and repeat, what I believe was a flashover detonation event at temperatures below zero. Cases showed minor pressure signs with a load that should have been in the 45Kpsi range. The most notable effect was a bent op-rod, so something weird was definately happening with the pressure curve.
Shotgun ammo has been another problem area. I've had frequent bloopers, or noticeably underpowered shots with both reloads and factory ammo. Faster burning powders seem to be a somewhat suitable remedy for this. My best luck with extreme cold shotgun ammo has been with old fashioned nitro card loads combined with faster flake type powders.
With many of the old standard extruded rifle powders such as IMR 4064 and 4350, I've had no apparent issues, although I suspect a chronograph or 300m target would show some deviance from more standard conditions. Surprisingly, my pest control load for the cabin 30-06 of 14 grains Unique pushing a 110 gr carbine bullet shows no noticeable difference from 90F through -30F.
With handgun loads, I haven't been able to induce any serious malfunctions, but noticeably dirty burning and decreased accuracy with cast bullets and increased leading have been apparent. Seems the cold does something to cast bullet lubes. Coated were even worse. I fired a number of coated (ACME) bullets last winter at temps around -15F. I recovered the bullets from a snowbank in the spring, and it appeared the coating had flat flaked off. Predictably a seriously leaded bore after some 30 rounds was the result, this with a moderate load in 9mm.
Has anybody else explored performance at extremes of temperature? Especially interested in chronograph results (do those even work at 20 below?).
