Just unlucky. I'd say you're at that point of you needing to settle on a 'good enough' prefix for the weapon. Something that increases firing speed or damage would be best in this case.
Terraria Community Forums
Techhunter_Talon
Augustulus
You actually used 296 platinum on that? I'm assuming you used platinum bars to make it since there's no way you can use that much money without getting the reforge.
neoselket
You can't make platinum coins with platinum bars.
Augustulus
I was assuming he made a tactical shotgun with platinum bars which isn't possible, since the Tactical Shotgun is a Post-Plantera drop by the Tactical Skeleton which spawns in the dungeon after Plantera has been defeated. Platinum is an alternative to gold when it comes to ore.