Why were the no 4's cut and the SMLE's left alone?
If you have some old barrels that are so worn out that they are useless I know some knifemakers who might be able to recycle them into something worthwhile.
The barrels on World war milsurps are good carbon steel. Good steel is cheap but
the guys who make damascus often use old gun barrels. 90% of the reason they would want them is sentimental. I think a lot of the people here could appreciate that a damscus knife made from forged together Enfield and Mosin barrels would be a bit more special than damscus made from railroad tie and volvo leaf springs. Boker even sells a modern folding knife made from panzer barrels.