You don't need money to take the time to properly test everything. Simply making a rent a gun feature for new guns so players could pay for one short trial of using it, you could see if its over powered. The entire era weapon system is flawed and makes it harder to balance weapons anyway.

And dragon rider your analogies are horrible. It is humanly possible to test the weapons and figure out what's overpowered and fix it before releasing it. If you change a weapon all the buyers deserve a refund, as people bought gralat packs with real money and purchased the gun and the gun was nerfed I'd say this violates apples guidelines.