What don't I know about this?
Can you not sell these on Ebay or is it not going to a FFL
Or What. Thanks I need to learn something today 
Here's their policy on firearms and parts, frame and receivers are not allowed.
Tim
http://pages.ebay.com/help/policies/firearms-weapons-knives.htmlActual firearms can't be listed on eBay. However, many parts and accessories for firearms are OK to sell, but only under certain conditions. See the list below for more details.
Allowed Caliber conversion information or blueprints
Magazine holders, speed loaders, stripper clips, or moon clips
Manuals or instruction materials about firearms
Non-pneumatic spear guns
Restricted Accessories and parts for guns such as butt plates, cases, cleaning supplies, dies, grips, holsters, molds, racks, pistol grips, scopes, slings, stocks, storage cases, or trigger guards. The listing must include a description of the type of firearm the accessory or part is for and what it's used for. If it doesn't, the listing may be removed.
Muzzle loader or black powder gun parts or accessories, as long as each item is offered in one listing at a time. (However, having separate listings for items that can be used to build a gun is prohibited.)
The following gun parts and accessories are allowed on the eBay US site only. The seller must be in the US and offer domestic shipping only:
o En bloc clips
o Barrels
o Bolts
o Choke tubes
o Cylinders
o Firing pins
o Hammers
o Magazines with a capacity to accept 10 rounds or less (high-capacity magazines that can accept more than 10 rounds are not allowed)
o Slides
o Trigger assemblies
Not allowed Firearms regardless of their ability to fire, how old they are, or their status as collectibles
Firearm frames, including grip frames
Firearm kits that are used to create a firearm
Firearm receivers, including parts, upper or lower, cut, or 80 percent receivers
Flash suppressors
High-capacity magazines with a capacity to accept more than 10 roundsor magazine extenders
Pneumatic spear guns
Powerheads, stick guns, or their equivalents because they work like firearms
Sears
Silencers
Starter pistols or blank guns, regardless of their markings
Zip guns