Gotta be a lot more specific than that!
More information about DeVilbiss spray guns can be obtained from the official DeVilbiss spray guns website, There is a resource section located on their website which offers a wealth of information about DeVilbiss spray guns.
No information
What kind of information?
One would be able to find out more information about m4 airsoft guns online on Amazon. Two other sites that have some information about m4 airsoft guns are wikiHow and HobbyTron.
Information on 45 caliber guns is available on websites that sell guns, for example Cabelas', and also websites of arms organizations such as the National Rifle Association. Information is also available at the website The Gun Zone.
An internet search will turn up some information.
For information on WW2 BB Guns see: http://www.theworldatwar.info/ww2airsoft.html
BATFE has that information.
Information not available to the public
Need more information, such as type of firearm, etc.
Try e-gunparts.com
Look on Nerf.ea.com to find out more information