Ok guys, Clark didn't say his 500 WAS not regulated, but curious about dual loads. Clark did say he was NEW to DR, just as I was last summer. Chances are he has not worked up a "regulated load". It took me all summer to get my .375 to regulate with different bullet weights. I would also say, that on some days my shooting was not up to par. I takes great skill to perfectly shoot 6 rounds in a row. If you don't, you'll never know if your load is really regulated.
Let' face it - six bench rested shots with a .500 NE has got to rarttle your nerves abit.