My F-Open gun was a 6.5x47. It was ok. I personally think if you are going to shoot open you need more gun. But our range is 0-1000 yards. Guys have good luck with the 280 Ackley, 284, 7mm WSM, 7mm RSAUM and so on in that genre. We have a lot of guys that shoot 6mm Ack Rem, 6.5x55 Ack, 243...