A lot of exiles isn't defined down to the nitty gritty.
This is definitely a good question, but would fall under what I consider the spirit of the rules. We have no super strict policy on what item is tagged to what rep, but it would definitely be considered bad play to be carrying tags for 10 kegs of gunpowder in your front pocket only to pull them out on a mod yelling "Lets use these!!!".
I would recommend if you have an excess of items on your person that you have no chance of having all the reps for to leave them in a "gear" location. Maybe a chest at your bedside or a stash in the woods or something. Of course IG theft comes to mind if you're leaving piles of tags on your bed, but I would remember that this is Exiles and thieves tend not to do well in a shoot first ask questions second universe
The reason this is an important topic is because everyone should keep in mind that in Exiles the Rep is the item, not the tag. We have nothing on our tags stating that x rep relates to y tag except a proxy tag on guns. I would hope since LARP is an honor system that everyone would be consistent with what items they're using, and that no one is
magically switching tags out on the same rep.
Also, this brings me to another point. Reps themselves. The exiles staff is more than willing to let everyone borrow the occasional rep for a gun, chopper, etc... Especially for new characters or new guns, but moving forward everyone should be trying to bring their own reps to the game that would cover their necessities. I'm not asking that you have a rep for every little thing you possess, but if you are a gunslinger that likes pistols and rifles you should probably have a personal rep of each on hand.