Fill adapter to SCUBA TANK

Any one else have a problem seating the adapter to the K valve on a scuba tank, mine appears to not seat properly, causing leaks, finally got it to seat but then noticed there were minor burrs on the black mating section of the adapter. The other types I have to fill my guns are OK and if anything they are of better quality and better made. Any one ever set the fill to tank adapter to a Foster fitting and fill the reservoir that way. Thanks for any and all assistance, Larry New owner of a Talon SS.