Reloading Cannon Drums Inflight?
 

I noticed the Beaufighter model has the observer sat in the back with spare cannon drums? Can he replenish the guns and also is this the case for the bf110?

I assume so because the 110 cannons get reloaded.

Only it's a Blenheim, and doesn't have cannon but 303 cal MG.

I imagine there is a key to bind.

i think the 110 cannons aren't reloaded i think that stop firing due overheating

yup it gets reloaded

I think if you look at the drum ammo counters, they count down from 60 to 0, then a few seconds later are back to 60 again.

yes, tested it and yes it get's reloaded, now the question is How???

I'm really not sure. I know the Beautfighter cannons were reloaded by the guy sitting in the back, but have no idea if this is correct for a 110!
sitting in the gunner position I don't think I can see any cannon.
However, wiki says this:

2 × 20 mm MG FF/M cannons (180 rpg - 3 drums with 60 rpg, cannon were reloaded by rear gunner or radio operator during flight)

Yes the BF 110 Canons where reloaded by the rear gunner/radio operator:

http://users.teledisnet.be/web/mfe39146/MGFF0.jpg

You can see the MG/Cannon Drums in the back of the 110 if you're the gunner and turn around.

... and if you look down into the rear cockpit from external view you can see the spare drums. Just like in the the diagrams posted above.