The best shooting rounds I ever put through my 50BMG where 1945 DM AP, So I'm confident tht factory reloads will last a while......Sealing is up to you but I would protect it from moisture within reason.
Haveing said that I have quit reloading ammo any farther ahead than I have to for a couple of reasons
#1 For whatever reason the bullet seams to weld for lack of a better term to the case, usually not enough to raise presure all that much but enough to mess with the groups. The problem I've run into is that it is not consistant batch to batch some will weld more or less than others??? One way around this problem has been to load them a little long and then put them through the seater to shorten right before I want to use them.
#2 It ties up powder and/or bullets I may want for something else.
#3 The gun gets traded or rebarreled and I got a lot of ammo with not home.
#4 I HATE pulling loads back part.....almost as much as shooting reloads that are not grouping the best that they could be.