NON-threaded is 108390. Threaded is 10199. I recently purchased 2 of the Threaded versions. I read about horror stories on here about removing the adapter. I had zero issues with either gun. As soon as I took them out of the box I laid them on a thick towel, removed the thread protector, put the included wrench in place and gave it a solid "whack" with my palm and they both came loose with no problem. Put a little Superlube on the threads and reassembled them. Tried to remove them again and 0 problems. I would not try to leave them a little "loose" to try not to have an issue. The threads are not tapered. You wouldn't want it backing out on you while in the field and loose it. With the little wrench included field stripping would be no problem at all. Not sure why, and don't doubt that some folks have trouble getting the adapter off, but after looking at it closely, I really think it is attributed to being slightly "over-tightened" from the factory and really clean machine work on the threads. Only the flat to flat, and the ramp on the threading is providing the friction to stay in place. If I had to do it over again, I would definitely go for the Threaded, 10199 model.
