Make sure the rifle is equiped for the second human player(Not the host player) before saving. Save and then resume the game. The second human player has pistol selected and cannot equip his rifle.
Throw rifle on ground and pick up again. Now able to select rifle.
EDIT CSR Kryssar:
100% repro rate in this case:
1) start multiplayer session with 2 players
2) on server side - suspend (to save and exit session)
3) at the same time on client side player changes weapon from primary to side arm
4) in lobby resume game
5) client looks like he has primary weapon in hands but in fact he has side arm (seen by HUD, sound of fire etc.)
6) if he try to switch weapon he takes pistol then imedietly takes back primary weapon that still acts like pistol