Many think they have crates and crates of stuff just laying around.{They really don't}with the last two bk's they had moved as much out as possible, and made up as much as possible and sold it as soon as they could.You have a better chance today of finding some old suppliers overstock like Starks, Ruvels, Militaria sales in New York. Interarms and Navy back in the day.And of course gun show's, when you see 70 plus year olds and older moving items on. that they ratholed over the past fifty years.
Many times you can get lucky and find a few old cardboard boxes laying on a table with items marked 20 buck's.
And other times they know what it is and want big buck's, That you would say they can still own it and move on to another table.I can't say these are the best of times anymore.
unless you want a modern M-4 style> and that stuff is all over the place now.