Are non premium HH working against surface targets ? I managed to land nice salvo on
Arizona and it didn't take any damge.

You have the wrong hedgehogs fitted to your boat. Go to the gun menu and pick the
hedgehog with the 120 second reload time. Those are the ones that run on regular
ammo.

Ahhh... that would explain it. Does it say that anywhere in the reload window, or am I
just blind?

I should also point out that realistically, the only advantage the Premium hedgehogs
offer over the non-Premium ones is the shorter reload time; both sets are already so
effective against subs (and occasionally surface targets) that you rarely need extra
punch to finish the job. Using the USN non-Premium hedgehogs, it's very easy to kill
subs with single four-mount salvos from outside their range, and even if it doesn't kill
them it'll usually cripple them enough to force them to surface, making them easy
pickings. You'll only have problems against 900-SD subs and ones that know how to
fast-dive, but it's really easy to outsmart those.

What Sintri said. The 7x Hedgehog launchers, like mines, need premium ammo purchased at
the NF store.

I use the 5x ones for ASW. The ammo is expensive credit-wise (500 per shot), but doesn't
cost real $...

They be a needing the premium shells for them premium projectorars.