I totally agree that ammo is necessary. At some point I think TP will make better trading stock. Most of us gun guys already have ammo stocked up, and would want to hold onto it, rather than trade if off. Men are more willing to go without TP and will be very unlikely to trade ammo if ammo availability is decreasing.
Moss will still grow, ammo won't. Women in search of the comfort TP can give, can make a man's life fairly unpleasant, hence the value of it as trading stock.
Ammo is more important to retain, with ammo you can acquire much more of nearly anything unless the other guy has a better defensive tactics.
"You can get lots more with a gun and a smile, than you can with just a smile." AL Capone.
Keep the ammo, trade the TP, antibiotics, and other meds you have a surplus of. Water purification systems/items would be another good trade item.