So according their website here, this is their address
https://sergeantmajormunition.com/crm.asp?action=contactus
13216 Southeast 32nd Street,
Bellevue, WA. 98005
US
Based on google maps street view the building is listed as West Cost Armoury which is an indoor range.
https://www.westcoastarmory.com/contact.html
which lists the same address
you might give the gun shop a call and ask if they have heard of the ammo company since they are the actual building at that address.
but from my view, at this point, it looks bogus.
Whenever I run into something like this, first thing is to check contact info and make sure they actually list an address. then check the address on google street view to make sure it the actual store.