Most of the wrecked low number '03s for which Hatcher could identify the cause of the blowup were due to things like casehead failures with poorly annealed brass, often from wartime contractors without the experience and QC of an arsenal or ammo company. Or from trying to cram an 8mm cartridge into a .30-06 rifle, which takes a sloppy '06 chamber and a lot of effort, but some people managed. Or from the practice of greasing bullets to try to prevent hard metal fouling from cupro-nickel bullet jackets. In most traceable cases, something had to go wrong, the rifles didn't just kaBoom by themselves, they had, after all, been prooftested when built. But when something DID go wrong, it went very wrong if the receiver had been overheated in the factory.
If this one has served as a hunting rifle for 60 years and had not been scrapped by the Army or NRA before that, you might expect it to be ok with normal loads in sound brass. Look at the little ledge on the right side of the receiver ring. Are there any punch marks there? That would indicate the rifle had been overhauled and re-proofed. My Mk I has three such marks. Pull the barrelled action out of the stock. Look at the recoil lug where the front guard screw goes in. Henry Stebbins says a brittle receiver will often show chipping around that hole, where recoil slammed the action against the screw shank. Everything looking good is not a guarantee that it is not brittle, some of these actions have been broken by being dropped or hit with a hammer, but it has lasted a hundred years, it might go a few more.
The sight base was held on by a pin going through a "spline cut" in the barrel. If you have the original barrel and it has not been turned or drawfiled heavily to reduce weight and remove toolmarks, I think there should be two shallow grooves about three inches ahead of the receiver. One at the original location, one where the sight was relocated when the rifle was converted from .30-03 to .30-06. If it is a replacement barrel that was put on with its own sight base, there should be one such notch on the bottom of the barrel at that location. But I don't have pictures good enough to be absolutely sure.