In the United States, it is legal to purchase a gun online as long as the transaction is conducted between licensed dealers, and the gun is legal in the purchaser's state. The purchaser must also pass a background check and follow any other state or federal laws that apply to the purchase. This means that the buyer must physically pick up the firearm from the FFL (Federal Firearms License) dealer, who will conduct the background check and any other requirements of the state or federal law.

Step-By-Step Guide

1. First, ensure that you meet the legal requirements for purchasing a firearm in your state. This includes being at least 18 years old for long guns and 21 years old for handguns, and passing a background check.
2. Browse our website and select the gun you wish to purchase. Make sure you are purchasing a legal weapon in your state, and that it meets any other specific regulations that may apply.
3. Add the gun to your cart and proceed to checkout.
4. Provide the required information, including your name, address, and contact information. You will also be prompted to provide proof of age and a valid government-issued ID.
5. When purchasing a firearm, please provide us with the FFL (Federal Firearm License) information of the dealer you would like the firearm to be transferred to, if you are not able to pick it up from our store."
6. Review the order details and agree to the terms and conditions of the purchase.
7. Pay for the gun using a secure method of payment, such as a credit card or PayPal.
8. Visit the dealer to pick up the gun and complete the necessary paperwork. This will include a form 4473, which is used to conduct a background check and confirm that you are legally able to purchase a firearm.
9. Once the paperwork is complete, the dealer will release the gun to you and you can take it home. The customer will also likely have to pay the dealer a transfer fee if the dealer is different from the one they bought the gun from.

Note: The process may vary depending on your state laws. Be sure to check the laws and regulations of your state before making any purchase.