Many weapons become purchasable from Ammo Knights after reaching certain levels from playing multiplayer.

Weapon	How to unlock
.52 Gal	Reach Level 14
.96 Gal	Reach Level 21
Aerospray MG	Reach Level 6
Aerospray RG	Reach Level 28
Blaster	Reach Level 5
Carbon Roller	Reach Level 7
Clash Blaster	Reach Level 30
Custom Blaster	Reach Level 27
Dapple Dualies	Reach Level 26
Dynamo Roller	Reach Level 20
E-Liter 4K	Reach Level 20
E-Liter 4K Scope	Reach Level 30
Enperry Splat Dualies	Reach Level 11
Firefin Splat Charger	Reach Level 16
Firefin Splatterscope	Reach Level 25
Flingza Roller	Reach Level 24
Goo Tuber	Reach Level 22
H-3 Nozzlenose	Reach Level 29
Heavy Splatling	Reach Level 8
Jet Squelcher	Reach Level 17
Krak-On Splat Roller	Reach Level 12
L-3 Nozzlenose	Reach Level 18
Luna Blaster	Reach Level 19
Mini Splatling	Reach Level 23
N-Zap '85	Reach Level 9
Octobrush	Reach Level 10
Rapid Blaster	Reach Level 13
Slosher	Reach Level 5
Splash-o-Matic	Reach Level 25
Splat Charger	Reach Level 4
Splat Dualies	Reach Level 4
Splat Roller	Reach Level 4
Splatterscope	Reach Level 15
Splattershot	Reach Level 2
Splattershot Pro	Reach Level 10
Tentatek Splattershot	Reach Level 4
Tri-Slosher	Reach Level 15