We're at 3200 feet here so I get a little altitude bump. The only sure way will be to pick up a box and give them a try. I'm thinking a 1/8 would be sufficient for sure but we'll see how the 1/9 does. The Berger Twist Rate Stability Calculator shows a 73gr bullet at 2900fps with an SG of 1.64 which is plenty good enough. Does anyone have a 73 or 75gr ELD-M that they could measure for me? Thanks!