There was a guy from North Carolina at a gun show awhile back sells them. Kinda expensive but had 855 cans and 50 cans. Looked like a good setup. Can’t remember his name but if you’d rather buy one than do the trial and error thing you could look him up.
Hypothetically if one were to seal a gun underground, it should be packed in grease and wrapped in plastic. A section of tube 10 ft long buried, with the items at the bottom attached to a rope would prevent unwanted detection. Such as a metal detector.
Look at a Katadyn pocket filter. I've got two of these and they are great each will filter 13000 gals before replacement. Water isn't that hard to find, clean water is. Just my two cents
My two cents worth but I think it's cute that everybody gets a bob full of stuff but seems to forget about water, that and seeing how 70 % of America can't do a pull up I suggest they put a donkey in the pack to carry it. Great rant