Do you have the genric "designed to fit X200" which also fits the M3 and other lights? If so the X300 fits that one, lots of spare room and the length is not an issue. The body of the light housing has some extra space and you need to add some tension to it for the X200 or 300 IMO but length is a non issue. Also, for anyone that does not have the holster already Id reccomend the SLS/ALS combo as it secures your handgun without the light installed much better.