The adaptor I have, is a genuine "leadloc" patent!, the lead end has 1, a back nut ,2, a dished copper washer,3 a fibre washer and finally,4 an "o" ring ! I have been told: back nut first onto lead pipe, then fibre washer, then dished washer and then "o"ring! I have also been told, backnut first followed by dished washer, followed by fibre washer and then as before the "o" ring is fitted last.
Only one of these can be correct

.
does anyone know or have used the item I describe?