Bear72, The barrel length has to do with the recoil and the muzzle blast. The shorter the barrel the worst it gets. You can read more on this web page. www.chuckhawks.com/7mmWSM.htm
The ultramags have a lot more powder capacity than most other cartridges and in order to burn all this powder a longer barrel is required.The reduced muzzle blast is a result of the longer barrel not the reason for the longer barrel.
Remington barrel length??
