Some of the new *green* lead-free ammo [no lead styphnate in the priming compounds] goes dead in as little as 3-5 years. Get Wolf [Russian/Serb] or surplus ammo if you can. If you HAVE to store components, buy double what you expect to use, [2 M2A1 ammo cans worth, at least] and replace half of it annually, using the other half, which will give you some idea of how reliable it's remained.
So you’re saying that since the theme of my collection is “Rifles of the Armies of the English-speaking World of the First Half of the Twentieth Century”, I’d do well to stock up on the LC and HXP ammo the CMP is selling?