Can anyone ID this box ?

[rnixartillery]

I recently extracted this box from the depths of my workshop,it has 'AS 50' etched in each end with wire rope handles and leathed grips,can anyone tell me what it is ?

 

[LCplCombat]

Is there a number burned into the bottom? I'll take a wild stab and say it will begin with a M. If so its for explosives. Is the metal work brass?

Can you measure it?

 

[hangarman]

ammo box

Looks Naval to me . Buff painted with a red band on the end,wire handles, but dont have any idea what it carried originally, sorry.