Thanks.I have the fatdaddys 510 and a chi you flat top cap.I got the spring contacts from Mouser,wasn't sure if you had to do a lot of modification for it.Fatdaddy's is suppose to be getting a spring loaded 510 that looks great,but I'm sick of waiting for them and want to get my DNA30 built.For that 510 yes, just enlarged the hole a touch and press fit the pin. That derlin also fits the chi you top cap from fasttech. It will require some shortening to fit in that one. But the same ideas apply, just have to cut down the length a bit.