I originally planned to use 243WIN for F-Class and did so for 3 barrels. It's a great cartridge, but I'm getting the same velocity (2950ish) with a 6BRX that uses 6 grains less powder. If you are already concerned about barrel life, then there are better choices than 243WIN: 6.5x47, 6XC, 6BRX, 6BR. For F-class, the 6BR rules the roost out to 600 yards and will give you 1000-1500 more rounds from your barrel.