Re: Sling and shooting positions?
I really enjoyed watching this bit of "Americana". What's revealing is that marksmanship facts have been around for a long time, perhaps, since the invention of rifling. These facts have not changed. What's changed is the thoroughness of training. Some marksmanship facts have been lost over time. I think this training film could get today's shooter off to a good start to becoming a marksman as well as any modern curriculum.
One thing though, I think some facts are lost due to realities on the ground precluding their consideration. Take for example the loop sling, if there's no chance of using it, teaching it could be considered pointless.