Thats why yeah their be should scattered weapons, like how it is now, but big caches of persay lmgs, rockets and fully automatic rifles.Enough to gear up a 20 man clan, would be a tantilizing reward and thats what i envision. Also their would be some caches that would be unused due to zombies overwhelming the base and also in a zombie scnerio uninfected humans and ammo are more valuable than weapons, so if they retreated especially in the early days of the infection large groups of weapons would remain. Also some miliatrys store older weapons to either has as backups or to destroy and for parts. Lots of old c7's (m16) are put in indefinite cold storage or to be sold/ given to other nations or to have as replacment parts.