'Msta-B' howitzers in combat action

I swear that based upon how hard these fire, that because of the developments of metallurgy, heat treatment, engineering designs etc., powders and munitions - and their driving bands, and rifling etc., that BIG cannons fire as hard as modern rifles - or close to it, with very high breech pressures, and FAST round velocities - they sound like a BIG rifle, with a "POW!" and a crack, rather than a "BOOM!".