BudsGunShop.com - Barrel

Steven, can't find weather it's actually stamped 308 or 7.62×51. this can fire both 308 and 7.62×51 though. On Springfield's website they refer to this as 308 so I'd imagine it's stamped 308. You can contact Springfield at 1-800-680-6866 or you can email them at (cs@springfield-armory.com) for a definite answer. Hope this helps some.

Hi Steven and welcome. Yes Sir it is. Springfield states in the owners manual : The M1A™ is designed and built to specifications to shoot standard factory .308 made to SAAMI specifications or 7.62x51 NATO ammunition. The specifications for standard
military ammunition include harder primers to withstand the slight indentation from the firing pin when the bolt chambers a cartridge. This slight indentation is normal.
The use of civilian ammunition with more sensitive primers or handloads with commercial primers and/or improperly seated primers increase the risk of primer
detonation when the bolt slams forward. This unexpected “slam fire” can occur even if the trigger is not being pulled and if the safety is on. Use of military
specification ammunition will help avoid this. Cheers and stay safe!

Steven, not sure if barrel is stamped 7.62, but you can fire common 7.62X51 military ammo in any currently produced rifle chambered for .308 Winchester.
On The SA armory website, it clearly states the Caliber is .308 WIN (7.62x51mm NATO). >>> springfield-armory.com/m1a-series-rifles/m1a-scout-squad-rifles/m1a-scout-squad-308-rifle/
Stay safe & have a great day!