In most U.S. states, you can sell to any other individual who isn't a felon. You can also sell to a dealer, and you can sell online on a gun aucton site like gunbroker.com
gunlistings.org armslist.com
100-300
No.
No, they do not
No, Sam's Club - which is owned by Wal Mart - does not sell firearms. Wal Mart does sell firearms, but only long guns.
No guns or ammo
The company Beretta sells sportsman gear. They specialize in the sale of firearms and also sell all accessories for the avid sportsman. This ranges from firearms to clothing sales.
No. See related link at the bottom.
It still is being used
Provided you meet all the requirments, yes.
Brownells sells firearms and firearm accessories.
Gunbroker.com, auctionarms.com. gunsamerica.com, "want to sell" threads on firearms related forums.