Should have clarified the terminology I am using:
P08 for Pistol of 1908 = 4" barrel
Navy = 6" barrel, used for this blaster
Artillery = 8" barrel
Gotcha. WE-Tech calls all of their airsoft pistols of this style the "P08" and then defines the barrel length afterwards.
http://www.weairsoft.com/guns/gas-blowback-guns/pistols/we-p08-series.html
The 4 inch has a fixed rear sight which is incorrect.
The 6 inch has the correct adjustable rear sight.
The 8 inch has the rear sight on the barrel (again, incorrect).