It's painted a gloss OD green, and has "CHEST, M14" stamped into the lid. Hinges are on the back end, and there's a hasp in front that catches on a rotating catch.
Inside, there's a padded stabilizing bracket in the center of the lid, and there are two holding clips to either side of that bracket.

In the body of the chest, at either end, there is a bracket shaped in a curved "double s" pattern - 3 high sections, 2 low. These are alos padded.

This was described as magazine storage, but it appears to me to be for something else. Anyone recognize what this is?

There's lots of stuff nomenclatured M14.

I doubt this has anything more in common witht he M14 Rifle than the M1 Rifle (Garand) does with the M1 Tank (Abrams).

-- Chuck

have you got a pic or dimensions of the case.

man, i hope it's something cool.

How's that?

i don't have a clue what that is...
btt so maybe we can find out.

It's a piece of artillery BII.  Shows up on the M190A2 M109A2 (etc.) data sheet:

1240-00-654-6089 Chest, M14

I'm not sure what it holds, maybe aiming stake lights.

Nada do do with the M14 Rifle.  Do a search on the NSN and the M109 howitzer BII purchase sheet will show up.

-- Chuck

Aha. Well, thanks for the info, Chuck. Wasn't the answer I was hoping for, but oh well...