portage dog wrote on May 22^nd, 2020 at 2:35pm:

Cool stuff ST.  I line the inside of my GG#4 pack, bottom and sides with a closed cell pad (old GI issue....) for my two 30L barrels to protect them as well and more importantly, my back. It also gives the pack some structure, making it easier to insert/remove the barrels at camp. The bottom pad helps keep the hard barrel edges/bottoms from creating circular wear spots in the pack material.  Last year I switched to CCS single barrel packs...much lighter to carry that two 30's... and pad the bottom on those as well.  pd

   ;D ;D ;D
  Great minds think alike ::) ;D ;D

I have a 2" thick close cell foam pad on the bottoms of both my food pack and gear pack. A little cushion if you drop your pack or fall on rough ground.
I figure with that foam and the way I pack my gear in zip-lock 3-gallon bags, If I ever dump over my packs will float nicely. ;)