Currently, entering a public match after going into the custom lobby leads to the loadouts from the custom lobby being the ones used in the game, not the public lobby loadouts. I tested it three times with three separate lobbies and the problem still pertained. I'm uncertain if this is applicable to Plutonium - and if they are even able to fix it - but I imagine fixing it would just involve a check that the loadout being used is the public lobby loadout. The bug allows users to use previously locked weapons in games if a locked weapon loadout is made within the custom games loadout creator.
*This may be intended behavior, in which case, ignore it