Thanks for the replies, guys. From further information it does seem that they're from the 'heavy' 7.62x54R ammo. I just bought 860 of them for a little over $5/100 shipped.
"For a man, be he ever so much resolved to do his duty as a parent, can't be flogging his children all day....."
The Memoirs of Barry Lyndon, Esq. (William Thackeray).