The 1:10 twist works fine for bullets up to 100 grs, but with heavier/longer bullets on the horizon it might be prudent to choose a faster twist. I think if I was to buy a new .243 barrel today I'd choose a 1:8 or even 1:7 twist. My 1:10 won't shoot 107 gr MK's or the old 100 gr X's, and now there's 115's available.