2506 wins hands down. 120 grain Speer hot cores flatten deer. Buddy uses his for moose and elk, after I turned him onto it. Prefers to be loaded warm, and will reach a long way. Blows the doors off of the 243 on the larger deer. Mega components available for it. Owned a 243 and shot a couple deer with it. Didn't impress me at all. I have had so many bangflops with the 06 that I quit counting. Much better in windy conditions and will totally ruin the day of whatever you are shooting at.