Woops! This was patched recently, it only requires 10 jumps now. The store text hasn't been updated yet, but I'm holding off on any new updates until I figure out why people are losing their upgrades. EDIT: Fixed the upgrade loss bug. The store is now updated to reflect that only 10 jumps are required.
Your weapon gains XP just for being equipped. So if you run through the 5th mission on the 2nd planet over and over, you'll get level 5 on any weapon in a very quick time period.
Honestly, I was very disappointed that the weapons don't change their form when you master them. That'd be awsome, I'd probably master every weapon if that were the case. Amazing game none the less 5/5
 "Utans Defender Mavas")
 "Clicker Heroes")
 "Idle Blacksmith")
 "Executioner 2")
 "AdVenture Capitalist")
 "Idleplex")
 "SpiroStudio")
 "Dillo Hills")
 "Versus Umbra")
 "Cactus McCoy 2")
 "Step Seq.")
 "Zombie Minesweeper"){kind=logo}
 "Magnetic Defense")
 "Them Coconuts")
 "Miami Shark")
 "Garden TD")
 "Deep")
Woops! This was patched recently, it only requires 10 jumps now. The store text hasn't been updated yet, but I'm holding off on any new updates until I figure out why people are losing their upgrades. EDIT: Fixed the upgrade loss bug. The store is now updated to reflect that only 10 jumps are required.