Cheers Gary, I reckon it's either been refurbed or refinished after conversion for L4 mags. The seals look really fresh with no signs of dirt and grease as is usual. The box would have been carried by one of the crew or more likely than not, the mags removed, box hidden away and the mags spread between the squad. The idea was that the L1A1 mag and the L4 mags were fully interchangeable and was a design requirement from the start. If that requirement hadn't been set in stone, the way the mag locked to the gun would have been designed a little differently but the designers were tied into it.