How is the .300 BLK almost as fast as 5.56 NATO?

I m looking at the numbers and it doesn t make sense. The .300 has about ten mm less case length (with no increase in base diameter) and double the weight, so why is it only about 200 m/s slower? Should it not be significantly slower than a 5.56? I m thinking it has something to do with the powder. If someone... show more I m looking at the numbers and it doesn t make sense. The .300 has about ten mm less case length (with no increase in base diameter) and double the weight, so why is it only about 200 m/s slower? Should it not be significantly slower than a 5.56? I m thinking it has something to do with the powder. If someone smarter than me knows the answer, then by all means I d love to know.
4 answers 4