If its stored properly, this shouldn't be an issue. Put it in an airtight container with desiccant packs. Should be good for 40+ years.
I am mostly questioning if match ammo looses any of its qualities over long periods of storage. assuming it is stored in ideal conditions.
I would also like to hear if anyone has wisdom and or had experiences.
I'm not sure how matches work so I could be off here. But is there a chance he custom tailored his load to the expected conditions of the match that morning?Since your question was about "match ammo", I will tell you that I have personally witnessed a National Champion (Mitchell Maxbury) loading his long range ammo in the rear of his vehicle the morning of a match. Both at Camp Atterbury and Camp Perry.
On the other hand, Mid Thompkins freely admits that he loads all of his wife and daughters ammo well before the season begins. They shoot this ammo all summer long. And they usually do pretty good too.
As for me, I am not that good of a shot. I load my long range ammo the night before.
I don't claim to be an expert on anything, but, I would be kinda leery running loaded ammo thru a tumbler. I had some .45acp ammo with green corrosion (verdigris) on it, I erred on the side of caution and took the ammo apart, dumped the powder, deprimed the cases (very carefully) then tumbled the brass cases. I always heard it was dangerous to tumble loaded ammo, because it could affect the powder & the way it burns, causing changes in pressure build up.I have shot old ammo, stuff that was 20+ years old that had not been stored properly and it sill fired. I even shot up some .22 LR that I found in a bunch of dirt and dust in the bottom of an old footlocker that was sitting inside a garage that was open to the elements. I ran it through a tumbler to clean it up and all but two of the rounds fired. I'm not saying that I would trust my life to old ammo but if I see some for sale at say an estate auction I'm not shy of snapping it up if the price is right. Besides, old ammo that misfires can be good for malfunction drills.