What?
80-item Limit
When loading up your Avenger for a massive UFO assault or arming soldiers for a Base Defense from your overflowing stores, you will likely hit this limit.
You only get a max of 80 items, and you don't get to choose which ones, so you may end up with 80 clips and no rifles for the base defense.
The solution is timely housekeeping. Sell off your spare personal equipment. See our handy Spring Cleaning Tips, and also Managing the Item Limit for ideas.
Another bug concerning this limit happens when there are unresearched (alien) items in your stores during a base defense mission. Even though the item cannot be used during the mission, the game still allows you to equip your soldiers with them. This rarely happens as the alien items are very low on the item list, but if your base is lean and mean with under 80 items total, everything will spawn regardless of research. (c) UFOpaedia