The M48 shorter length actions were Zastava of Serbia, military iteration under earlier"Peoples" factory name. Those days of latter twentieth century Herters WAS importing them commercially.
Their Roots of shorter length from Roumanian Model 24 actions first produced in Belgium and then with production equipment purchased from FN, their own Roumanian produced for their army. All this series were the 'bit' shorter action and FN continued to market such action length internationally as optional military contract optional.
Z, "Original FN mausers" as I use the term, reflect complete 'out the FN factory door' rifles marketed by FN as their own products. "FN original actions are more generic in the sense you express of going into all manner of branded rifles. Some FN actions without demarcation above the wood line as notably above! My belief a sufficient large order from some riflemaker which didn't want FN markings, prhaps to substitute their own, as reflecting the covert markings. I have a postwar FN military carbine with a beautiful FN receiver ring logo. The point that FN sometimes used convenient "off the shelf" components for certain runs within respective military or commercial genres.
Best!
John
