I did not feel unsafe firing either rifle, and it's clear that the armory didn't feel they were unsafe either as no great push was made to recall the early receivers. Both were brought home from France by the men who fought with them, local veteran's. I was lucky enough to acquire two all original as first issued M1903's, 1910 Springfield and 1913 Rock Island, I have fired both more than once, but not excessively due to the historical significance and high dollar value of both rifles. Uncle liked to rebarrel everything at the slightest sign of wear so most receivers on 1903's or M1's will not be wearing the same barrel it was first issued with, probably not the same wood or any other part either. You will only likely encounter a low number receiver on a WW2 rebuilt rifle, otherwise the only place I have seen them is on original rifles, and these are both very rare and expensive. Much more common are the higher number rifles made in large numbers during and after the Great War and later in the 1940's by Remington. The issue was with the heat treatment, not that the heat treatment was bad, only that the way it was done could have led to errors, maybe. A small number out of hundreds of thousands of rifles. A small number of these receivers failed during the Great War, it was never cleared up how many failed as a result of war damage or being fired with mud packed barrels. Low number receivers were supposed to be pulled from service as the rifles came in for periodic overhaul, given the number of WW2 era rebuilds I have seen that have these low number receivers still on them it's apparent that Uncle Sam wasn't afraid to use them. I wouldn't worry about it, receivers with the low numbers will be on the oldest and probably most expensive of M1903's.

Curved bolt for mosin nagant