Yes I think that is true, but exactly how much I don't know. I'm fortunate to own a .40 caliber MK9K. Dr. Dater said that Gemtech made somewhere between six and eight of them. When I bought it used it was set up as a thread mount for a MP5-40. I had the end cap changed to one with a 3-lug mount. Because the thread mount threads onto a Navy style barrel, the can might be somewhere around 1/4"-1/2" shorter OAL using the thread mount instead of the 3-lug. Now if your application was on a plain threaded barrel without a 3-lug, you might get the OAL an inch shorter.
IMHO the 3-lug mount is miles ahead of a thread mount. No worries about cross threading. The 3-lug mount is quick, easy and very positive. I have a HEMS II can for my Mark 23. After every 12 rd mag, I need to check for tightness of the thread mount. If I don't pull the can off when it is still warm, I can't thread it off when it is cool. If you have a Navy style barreled host, what little extra length you'd be saving using a thread mount is not going to have enough positive effect to make up for the downsides of a thread mounted can, at least to me. Good luck with your MK9K mount project.
Scott
