The "lines" on this brass end cap represent another form of knurling known simply as "straight knurling", if my memories of cold metalworking industrial arts classes are correct. Engine lathe work done at slow speed.
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David Longenecker R.K.C.C. #CM83 RKS#1691 N.R.A. Endowment Life Member Residing somewhere in the Ubiquitous States of Amnesia
I have found this picture on internet. It seems to be the original drawing that captain Ingraham sent to explain his design of the survival knife he proposed. I don't know if it has already been in the forum (I didn't found it) and don't know if it must be placed here. 'thought it was the best place. I'm not sure if it is the true original or a fake. Any ideas?
Thanks Chief. Zog, if you're looking for one shoot me a PM and I'll point you to where I got it. It's pretty well made and has the compass mounted in it.