I happened to be looking at the videos for the M*CARBO upgrades including the armorers wrench (that I ordered along with a few other things). In the video for the wrench, they show using the section for the thread protector. However, my new gen 2 has a knurled thread protector and not the "nut" type shown in the video. So are there two types of thread protectors? Which is newer? My gen 2 is in the FBHxx SN range.