Sometimes other things in our lives (besides guns) take priority. If you are selling to put the money towards an upgrade then congratulations. Others may need to free up cash for bills or other unplanned events. There are many reasons to sell, but everyone would like to get the most cash out of the deal. There are many options for selling your old guns. However, take my advice and NEVER sell to a retail gun store or pawn shop. They will take guns off your hands if you are absolutely desperate, but be prepared to bend over and settle for around 30-40% of what you paid. Then, they will turn around and sell it for 85%-90% of the retail price. Ouch!

The best way to sell your guns is either directly to other consumers (face to face) or online. However, you will have to deal with shipping it which can be a hassle if you are not familiar the process.

When selling used guns face to face, you (as the seller) are under no obligation to perform any background checks, fill out any forms, or ask any questions. In the great state of Florida, we are not required to register our firearms so you don't have to worry about that either. Selling guns is no different than selling staplers.

By cutting out the middle man (gun retailers and pawn shops) you should be able to leverage around 70% of your original investment. Depending on the make and model of the specific gun it may actually appreciate in value. Just like high-end cars, high-end guns hold their value.

Selling online is also a great option because you have a wider audience. Specialty forums like ar15.com and hkpro.com are great places to sell used guns. Most of them sell within a week, and sometimes even days or hours. There are no consignment fees and in many cases you can have your money same day (paypal). If you list your gun on an auction site like gunbroker.com you will have to pay broker fees and gunbroker offers no protection or guidance in the process.

If you sell your gun online, you will have to ship it to an FFL holder such as a gun shop, pawn shop or somewhere that can transfer the firearm to the buyer. Some FFL holders will allow individuals to ship directly to them. Others require and FFL to FFL transfers. Do your homework before sending the gun out. Call the buyers FFL and tell them what you are trying to do. They should explain the process to you.

A machine gun fires more than 1 rifle caliber round each time the trigger is pulled. A sub-machine gun fires more than 1 pistol caliber round each time the trigger is pulled.

Machine guns are more common among long range battle engagements due to the longer effective range of rifle caliber rounds. Sub-machine guns are often employed for close quarter battle (CQB) where the use of short-barreled weapons is desired.

These are popular rifle calibers for machine guns:

• .223/5.56 - AR-15, HK 416, FN SCAR
• 7.62x39 - AK-47
• 7.62x51 - HK 91, FN FAL
• 5.45x49 - AK-74
• .300 Blackout - AR-15

These are popular pistol calibers for sub-machine guns:

• 9mm - MP5, UZI
• .45 ACP - UZI, HK UMP
• 5.7x28 - FN P90, AR-15
• 4.6×30 - HK MP7

Read more about machine gun ownership.

The short answer is yes.  You can buy a used suppressor and have it transferred by completing the proper NFA paperwork.  However, seeing as it will take 4-6 months for the BATFE to approve the transfer most people prefer just to buy a new one.  Some people will offer to pay the $200 stamp tax for the transfer simply so they can unload a suppressor legally. The used suppressor market is not large in the United States. In contrast, some European counties do not control the sale or possession of suppressors. In these countries, they are widely used and are available second hand just as guns are in the states. 

Suppressors do have a working lifespan and will eventually wear out.  This is another reason people do not like buying a used suppressor.