precisionworks
Flashaholic
+1^^ Careful at the tail........not as thick.^^
The tail O-ring area on all full size SF lights is the thinnest part of the body. AFAIK the same O-ring dimension has been used since Laser Products started - 0.775" OD at the groove (19.68 mm).
I final ream all full size lights to 0.744" & so far everything fits inside that dimension (18.90 mm). I have an older Fivemega tube for a 9P that measures 0.750" (19.05 mm). Pretty similar dimensions.
As long as the tube is centered in the lathe as perfectly as possible the OD & the ID remain concentric, stresses are evenly distributed & the body remains durable.