Just buy it from a more sensible country like the Czech Republic, suppressors (and most firearms) are over-the-counter purchases with no paperwork or waiting period.
The goddess apparently does have gun law dodging powers though, otherwise he'd have been waiting 2-4 weeks for that rifle. They're supposedly coming from a store in America, but American gun laws are actually ridiculously annoying if you ever try to but a gun, so she's either somehow avoiding all gun laws or is actually obtaining everything from somewhere with actual common-sense gun laws like the above-mentioned Czech Republic.
...I have no idea where you're getting you're information, but no. According to chapter 1.1, the goddess is working at an outdoors supply store in Arizona. There's only 11 states that have waiting periods for firearms and almost all of them are notoriously shit places to live (California, Colorado, Washington (state), Illinois, New Jersey, etc.). Arizona does not (Florida, fucking bizarrely, does despite being known as the "Gunshine State"). You walk in, and the NICS check takes about 5-10 minutes and you walk out with your firearm. I've bought firearms - yes with a federal background check, and yes, they already exist and are mandatory - in less time than I've waited for food at McDonald's. That's how it is in 38 other states.
As for common sense gun legislation... We can own shit in America that you will not be able to own in the Czech Republic. I'll take a Form 4 and a 6+ month wait for the ATF in order to buy a suppress and to actually have a sanctioned right to firearms and the ability to purchase machine guns, destructive devices/explosives, etc. I looked through some of the Czech Republic laws and I see a
LOT of regulations and licenses and restrictions that do not exist in America (federally, at least, you don't move to California if you like firearms).
Is it bullshit that I have to pay a $200 tax on a can and wait months for approval? Yes. Would I trade it for the Czech Republic laws that are more lax on suppressors but vastly limit my right and ability to buy what I want? Absolutely not. Ever.
As much as I respect the sportsmanship of hunting, got the same beef with this manga as I got with theHunter: call of the wild.
Why don't you use a silencer?? I know they exist for hunting, and the gun loving USA must have them
Can probably also get a hunting pistol and crossbow too
Suppressors are not really viewed as good sportsman like use. It varies from state-to-state. Some states allow them. Some don't. Suppressors are also not really going to be quiet enough on firearms you'd actually use while hunting game to make a difference in most cases. Unless you're running something specifically meant for suppressed use and sub-sonic like .300 Blackout.
It also doesn't help that buying a suppressor means sending off a form to the Bureau of Alcohol, Tobacco and Firearms and waiting 6-12 months for them to say you're "allowed" to actually accept possession and ownership of the suppressor you've already paid for.
