This one was requested by ricardoumezu ...
I don't know how big this is meant to be...the uploaded files should give you a weapon about 300mm long. If it needs to be bigger or smaller, scale accordingly in your slicer.
The cylinder is supposed to rotate out. I haven't made pins to allow this, but the cylinder is not fixed in place if you want to try and add pins to this.
Parts run through netfabb, so should all be printable.
And yes, the observant among you will have noticed that the rendition of the full gun is missing the hammer...I just forgot it, but don't worry, it is included in the stl files. :)