Back in the late 40's, the military was dumping a lot of surplus WWII powder in the ocean to get rid of it. Hodgdon decided that the powder could be used for the handloader if made available. He came across 80 tons of powder that was being rendered from British 303 ammo. He named this powder BL-C, the C meaning that it burnt cooler than the IMR powders. When this lot ran out, he got the original formulation and had it made but marketed it under the name BL-C2 as it was the second lot of powder. All things being equal, it is the exact same powder as BL-C2. As with any powder, I'd try a few rounds of reduced volume and work back up to your normal loads. While a stable powder, it is near 60 years old or possibly older. Frankly, I'd keep it as a collector item rather than using it.