Red BAroN
Depending on how much you bought it for and who makes the gun. if it is full metal than there is a good chance it does have the blowback feature on it. You should ask the guy where he got it from and how much he paid for it.Or check out this link to see if you can find your pistol and learn more about it

Joe Jeronimo
You should not have bought from ebay first of all. Those sellers can't always be trusted. I get all my stuff from airsplat.com because they split their site up in to blowback and non-blowback. It's really much more convenient.

I am grunty
It's called the slide. The cartridge in the brass used to house the powder and bullet in real-steel guns. This depends on the model. If it's anything other than an NBB gas or CO2 pistol, the slide WILL move.