Folks,
I've got two No.1 rifles in .243Winchester and a 1V in .22-250Remington.
One .243 is a 1a the other is an RSI. I've read where some folks use them for long distance. Mine are both 10 twist so bullets over 100 grains don't stabilize. The .22-250 is a 14 twist. Although I haven't tried anything over 53 grains wouldn't you need to be in the 70-grain weight for over 400 yards?

Thank you in advance for your time and help.
Semper Fi,
Soup