Putting some FIP Dahl stop valves onto brass MIP threaded adapters (to PEX-A). I notice when I screw the valve onto the fitting it goes on about 3 turns before it gets hand tight without tape or thread sealant (not ready for final assembly -- just testing to see if the threading is good on both parts). I'm guessing a pair of wrenches and some teflon tape will get me maybe one more full turn... Still a lot of thread showing on the male adapter. Is that normal? Should it thread in more deeply or is it normal to have about half the threads exposed on the male adapter when completely assembled? I've double-checked the labels for thread type -- both pipe thread so I assume they are compatible and meant to work together. 