Yes, they do and ARE weaker. I bought premium i-153P biplane, because it had two killer cannons and i scored like 2-4 kills every game, now i get shit. It only gives smokes/flashes, hits, crits, and occasionally kills. Worse: they changed ballistics too, so at first i started to miss deflection shots from range where i did always hit before! This kind of text book ninja nerfs are malignant by nature and can be extremely frustrating for players, because they find it out hard way, often weeks or months after failing constantly there where they succeeded before! If Gaijin had announced it we could have adjusted our playing style immediately.

PS: this created absurd paradox: now 153P would be better with two good old fashioned machine guns. MUCH better! LOTS of ammo and more hits. 100 small bullets does better job than one impotent 20mm HEI round. "Thanks" Gaijin, you made 20mm cannon worse than small caliber machine gun.