new to .308

I have found a decent load with BLC2 but im worried about temperature change. How big of a deal it really is? half a grain makes the difference between 2 inch group and 5 inch group for me.
 
Below fps change for each degree F (BLC2 will be very close to 748)

33XPgx3.jpg
 
Below fps change for each degree F (BLC2 will be very close to 748)

33XPgx3.jpg

Thanks, I'll save this. So basically 1.12 FPS change per 1 F degree for W748/BLC2? According to this chart W748 is just as sensitive than IMR4895 and I don't hear much about IMR4895 temp sensitivity. Very interesting.
 
Thanks, I'll save this. So basically 1.12 FPS change per 1 F degree for W748/BLC2? According to this chart W748 is just as sensitive than IMR4895 and I don't hear much about IMR4895 temp sensitivity. Very interesting.

The older cartridge below was loaded with RL15 and 1.52 on the chart above.
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 noticeable muzzle flash and temperature sensitivity led to the development of the MK 316 MOD 0 for Special Operations use.

Below the newer cartridge is loaded with IMR-4064 and 0.45 on the chart above and better suited for long range sniping in Iraq and Afghanistan.
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 (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).

IMR-4895 is a much older powder from the 1930s and H4895 is a extreme powder at 0.23 vs the older at 1.10.
 
IMR 4166 shoots as well as Varget.

That's what I am experiencing ...but for the kissing cousin 7mm-08. Can't compare 4166 against drastic temperature changes yet but I am surprised at how accurate it is in this rifle with the varget "hunting" load component combination...and without load tuning yet.

Regards
Ron
 
The older cartridge below was loaded with RL15 and 1.52 on the chart above.
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 noticeable muzzle flash and temperature sensitivity led to the development of the MK 316 MOD 0 for Special Operations use.

Below the newer cartridge is loaded with IMR-4064 and 0.45 on the chart above and better suited for long range sniping in Iraq and Afghanistan.
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 (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).

IMR-4895 is a much older powder from the 1930s and H4895 is a extreme powder at 0.23 vs the older at 1.10.

Thanks. I know temp sensitivity is a key element in ammo for the military because they expect to be in theatre of all kind of climate from extreme cold to extreme hot. I just wonder if IMR4064 will be just as good in the shorter 18.5'' barrel or if I should use IMR3031 instead.
 
Barrel length makes no difference to powder choice. Use either 3031 or 4064. Both meter poorly, but if you are weighing each charge, no difference. If you want to throw powder charges, use a ball powder like H335, BLC2 or 748.
 
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