Be sure to fully seat the atty on the K100 FIRST before tightening the battery down. The K100 has a floating pin, so you want your atty sitting flush before you adjust the body. If you neglect to do this then your atty will only be held on by the
threads (which isn't a big deal if you are running a cart inside the drip shield, but if you have say an Ithaka or similar, can potentially bend / strip the 510 connection) and won't have the added support of the outer diameter of the K100's mating surface