Has anyone ever used food saver to store ammo in the airtight bag

I have not but it should work fine. Typically I use ammo cans and even my bulk loaded ammo that's loose in them stays nice shiny and new looking.

Vac seal then put into ammo cans would probably be even better if over kill.

I guess it would work just fine.

For bulk handloads, I use 2 gallon buckets from Lowes. Not too heavy and they stack great.

For precision handloaded ammo, I use those colored caliber specific ammo boxes. I can't remember the brand.

Now you got me thinking about sealing a few packs up.

Probably mec brand but then again there are several

I just cracked open a wooden case of loose, surplus 7.62x39 that I've had a barn loft for over 30 years, extreme hot and cold cycles. And no telling how old it was before that or how it was stored.

Only shot a few hundred so far, but every one has gone BANG.

I have done it with 10 shotgun shells in bags to take on canoe duck hunting works great for that

I've shot 12 gauge shells that were 30 years old. The ones on top were noticeably dirty, the rest were fine. I've never had an issue with metallic cases ammo. Stored dry is the biggest issue. Plastic can lock in moisture potentially.

For this I just used one of the plastic ammo cans from rual king. Keeps it dry and you can put shells up when done. The plastic is lighter than steel ones and doesn't make as much noise in an aluminum boat

I was thinking for long term storage by using the vacuum pack then storing in ammo cans maybe it’s over kill but shouldn’t have any moisture getting in and causing problems

MTM is one brand, but they take up a lot of space. I use the classic "ammo can's"

I have I did a brick of 22lr

it probably didn't see harsh enough conditions to make a difference but I had some go questionable in my van some years back

a year in the van just in cardboard and the humity got to it and went from the same case of ammo having maybe 1-2 in 300 failure to fire to about 1-2 in 30 failure to fire.
they were packaged in 325 round packs lead round nose 22lr

I don't keep 22 ammo of that quantity in the truck any more and I keep most everything in a plastic bag to help keep moisture out just gallon ziplock freezers that is mostly shotgun shells I keep 1-2 of the 100 round packs of ammo for dispatch or other around the farm use in the console.