OK; riddle me this...
 

What's the little pouch or pocket in a leg o' mutton case for? I used to think it was for the forend but I alwaysleave mine attached to the barrels, and really it's too deep for the forend anyway.

Wooden cleaning rods.

Yeah, kinda what I thought. Kinda big for that though...but whatever.

I can remember my father' GHE in a leg-o-mutton and the wooden cleaning rods and attachments were neatly rolled up and tied in a canvas type envelope and in that pocket

Cleaning supplies and rod, Snap caps, Leather forend guard, chewing tobacco, whistle, hunting license, liquor bottle, and any other hunting accessory you can think of. I have found all of the above in side pockets on vintage cases.

Right-On Jim !
The Canvas Roll, for all the cleaning stuff (rod sections, brush & jag), protects the barrels and is why the pocket is so deep. To bad the cleaning gear roll is missing from most all old LOM cases.

Cleaning rods were either two or three piece and lengths varied