Wing 20mm Cannons on FW190

[Jon]

Can some one please tell me where the compressed air bottle to activate the wing cannons on a FW190A-5 were situated...obviously in the wing but where exactly?

Also in general : If a cannon was armed on the ground and cocked by the armourer before take off and, i assume the cannon, on firing reloaded and cocked itself due to the blow back from the round infront when fired, like on any self loading weapon....what exactly did the compressed air bottle do?