Hard to imagine anyone in this field of interest who does not know the name TONY WILLIAMS .
A prolific writer in the field and author of several really interesting and authoritative books including :
The Assault rifle
Flying guns WW1 ,WW2 , Modern era - 3 books
Raid fire - Machine guns - aircraft cannons
He has a web site with great photos and very few errors which has worldwide exposure. I have seen it cloned in Chinese , Japanese and Korean.
Since he started consulting the error level in this field has gone way down.
I encourage anyone interested in this field to buy or borrow his books and visit his web site. Great work !
A bit light on headstamps for my taste but that is “inside baseball” for ammo collectors.