Berdan-Primed Ammo
Berdan-primed ammo is popular in military surplus ammunition and ammunition from countries and militaries outside the United States. While berdan-primed ammo is slightly cheaper to manufacture, it also renders the spent casings impractical to reload. Berdan Primers do not use the “anvil” – it is formed into the case head and thus there are two flash holes on either side of the anvil. This is what makes the Berdan much harder to reload.
If you intend to reload your spent casings or sell your casings to a reloader, don't use berdan-primed ammo (stick with boxer-primed). This is the reason many shooting ranges prohibit berdan-primed ammo. It isn't that the ammo is dangerous, it just causes them headaches (and money) when they try to sell the spent brass. The reason that berdan-primed ammo cannot be reloaded is due to the way the case is designed. When using berdan-primers the cup that the primer sits in is built into the case; this makes extraction of the primer difficult without damaging the casings.
Note: Sometimes (but not always), berdan-primed ammunition will also use corrosive or slightly-corrosive priming compounds. Just be sure to check prior to purchasing and make an informed decision. Some people don't mind purchasing ammo with corrosive primers, but they can be harmful to a firearm if the firearm is not properly cleaned after each use. Again, there is plenty of non-corrosive berdan-primed ammo out there - just make sure you are informed either way.