i actually think, that either the bulletin is broken and gives you more than 10% or the impression of its hugh impact is wrong. mg42s have a very high rof, so the 10% increase should only give you an actual 10% increase! will test it myself.
Well, if that extra 10% gives just enough boost to suppress with one volley instead of two (or little over 1) the impact is much bigger than the 10% would initially suggest. Reloading and cooldown take precious time which is very important during a flank.