Guys.....a little confusion here ...........
The US Iowa class 16" ordinance used silk filled cordite bags for the explosive accelerant & not pre rammed explosive filled brass shells
The British standard 4" MK X to MK X1V mounts used projectiles similar in concept to a .303 or .22 hand gun shell projectile, being pre filled & rammed & yes the brass shell casings were collectors items......
Whilst I have never experienced either of the above gun mounts firing......I have witnesses firing of 5"/54 calibre FMC mounts on our OZ DDG destroyers & I can assure you they are very
LOUD
It is all about the velocity of the projectile that determines the sound pressure level & the frequency...... Derek