6 months in the guns is my general rule. Then they get shot up and new ammo goes in.

To keep everything in perspective, I did an accuracy test about a year ago using a 1944 production Remington-Rand M1911A-1 pistol (73 years old at the time), shooting FC-63 ammo (Federal Cartridge, 1963 production GI ball ammo, 54 years old at the time). 21 rounds (3 magazines) fired at 25 feet, 1/2 scale B27 Silhouette target, possible score of 210-21X, my score was 205-5X. No malfunctions, no problems, just perfect performance.

Still have 5 full boxes of the FC-63 GI ball ammo, and I wouldn't hesitate to load it up for defensive use.

YMMV