The perfect caliber? One that shoots bullets with a BC of 1.000, the recoil of a .243, and stays supersonic out to 2500yd. Oh wait, you meant in real life. ****. Well, you could always go 338 Lapua or RUM. I have heard the 416 Barrett might be accurate too! Or, another snot beater would be a 375 RUM shooting 260gr Accubonds. Thats pretty accurate for me out to 500yd at least. Oh, dont forget, you can just neck up your 300 brass too.