Don't worry! Like most European rifle factories, Brno used the same outside barrel profile on all their production rifles of a given model, regardless of caliber. This eases production, as the same stocks, sling swivel rings and frontsight bases may be used on all. So a ZKK 600 in 9.3x62 has the same outside dimensions as the same model in .270. Result: The .270 with it's smaller bore is heavier than a 9.3x62! This is especially marked in the 602, when a .300 WinMag came nearly a pound heavier than the same model in .458 Win Mag! FI on my 602 in .458 the barrel wall thickness at the muzzle is only about 2.6mm.