Drone expanded ammunition bay...
 

Maybe I'm missing something but when I add a Large Weapon mount to a Roto-Drone... then add the modification 'Expanded ammunition bay: Belt'... then add a weapon, say an FNHAR assault rifle... The weapon still lists its base ammunition capacity rather that updating to 100 like the ammo bay mod says it should.

Any help would be greatly appreciated... Thanks.

Did you put the weapon on the mount on the weapons tab?

Yes, ammo capacity doesn't change from the 32 base.