Stupid Question?

[twh]

US manufactured arms were made with completely interchangeable parts so no need to serial number everything. The serial number being stamped on everything is more of a European thing. Special rifles like National match and target rifles initially had no numbered parts either but on later production when special modifications to parts began to be allowed the bolts, stocks and even trigger groups on the Garands were numbered because the parts were specially gauged and fitted to each rifle. Very simplistic answer to an involved question but gives you the gist anyway.