...was prepared to believe that this 18S case was a J Boss 25yr gold-filled...

...then I noted this Keystone? mark on the cuvette...

...then this on the frame...doesn't feel or sound like solid but I wonder...absolutely no brassing on the case despite wear...any opinions much appreciated...

J.Boss marked cases are always gold-filled. The trade-mark was owned by Keystone, hence the Keystone logo on the other lid. The "14K" indicates the quality of gold used in the gold layers.

We have another post on this very subject... will try to locate and post a link..

Got it on first search attempt

https://ihc185.infopop.cc/eve/forums/a/tpc/f/1...011013312#7011013312

...thanks fellas, should have done my IHC research work first I guess...again, thanks much!...Jim