First, let me congratulate you in coming through an experience which I have shared as unscathed as you did. In my case, I know what the problem was and was able to avoid it happening again for years in the future.
The year was 1960 and I was preparing myself for my first encounter with the Marine Corps, in the form of their Platoon Leaders Class, at Quantico, Virginia. I was due to graduate from college in a few days, and twelve weeks at Quantico was to result in my commission as a Second Lieutenant, prior to my starting law school in the fall. Although I had been firing center fire rifles for years, I had never fired a .30-'06, so this session with a M1917 Enfield was supposed to introduce me gradually to the increased recoil of the M1 service rifle then in use.
With economy in mind, my first loads were with cast bullets propelled by a reduced load of IMR 3031, the all purpose powder for my varmint rifles. I selected 30 grains as appropriate both for the 150 grain cast bullets, as well as some 200 grain bullets I also had available.
I set about loading the cases with my Belding & Mull loading tool, which for those not familiar with it, is a neck sizing only operation, with depriming and sizing as separate operations. Since I was going to use a Belding & Mull powder measure as well, I had a loading block to hold the sized and primed cases for that purpose.
For those not familiar with the Belding & Mull measure, it is a device which is capable of extreme accuracy, often used by bench rest competitors. However, rather than emptying the measured powder directly in the case, it makes use of a charge tube to hold the measured powder, which is then poured into the prepared case using a powder funnel.
As luck would have it, right in the middle of this exacting operation the phone rang and I answered it. Somehow in the process, I lost track of which cases were empy and which already charged. As a result, the cases in one row of five received no charge at all and another five received double charges.
60 grains of IMR 3031 is a slightly above maximum load for a 150 grain bullet, but it is dynamite for a 200 grain one. I don't recall how many shots I had fired before I loaded the fatal 200 grain bullet into the chamber, but it had been enough to zero the rifle and accustom me to the recoil.
The head of the case simply evaporated, and bits of brass were driven down the bolt raceway on the left side of the action directly into my face. When I recovered and reached up to feel my face, my forehead was covered with blood, and I thought I had but a few moments left on earth. Fortunately, that proved not to be the case, and I survived a sadder but wiser young man. I did graduate from college, I was commissioned in the Marine Corps and spent three instructive years on active duty, right at the time when the war in Vietnam, from which I emerged unscathed, was heating up.
I have understandably been leery of low numbered Springfields. Consequently, I have approached them with extreme caution. My understanding is that the only ones who are extremely dangerous even when fired with the correct ammunition, are ones which were improperly heat treated, and allowed to reach a much higher temperature than normal in the heat treating process, resulting in chrystallization of the steel and turning them into booby traps.
General Hatcher writes in "Hatcher's Notebook" (pp 214-5) that at first during the forging process the receivers were sometimes being overheated. Without relying on measuring equipment of any kind, the workmen were judging the temperature of the metal in the furnace by its color when heated. After an investigation of the cause of brittle receivers, pyrometers were installed in the furnaces, and it was established that temperatures judged correct "by eye" could be as much as 300 degrees hotter on a bright sunny day as on a cloudy overcast day. This was identified as the cause of the "burned" receivers with chrystallized steel.
Soon after the pyrometers were installed, the method of heat treatment was changed from single heat treatment to double heat treatment and double heat treated rifles and the nickel steel rifles which followed them were referred to as "high number" Springfields, starting at serial number 800,000.
There is an easy way of determining whether a low number Springfield is one of the dangerous ones. The act of drilling and tapping the receiver for a receiver sight or a scope mount will reveal whether the metal is hard on the surface and soft underneath, as it should be. Should the metal prove to be glass hard all the way through, then it is probably unsafe to fire.
General Hatcher's investigation of accidents with the Springfield at the National Matches revealed that one of the most frequent reasons for blow ups turned out to be the use of grease on the jacketed bullets to prevent metal fouling in the bore. The grease inevitably found its was to the neck of the chamber and built up to a degree that finally a case neck was unable to expand sufficiently to release the bullet, causing pressure to soar. Excessive lubrication of cast bullets could cause the same result, as could use of a slightly oversize bullet in a chamber with a tight neck.
Rifles do strange things. I was firing once at a match at Fort Benning, Georgia when I shooter down the line from me suddenly got up with his rifle and hurried to the armorer's van. The rifle he was firing, a pre-64 Model 70 Winchester, was missing the top half of the receiver ring and the corresponding top half of the barrel above the chamber. The shooter had fired a shot, had it scored, and was attempting to reload when he first noticed that the accident had happened. Obviously no barrel obstruction had been involved, since the bullet reached the target 600 yards away. The only plausible explanation seemed to be that there had been a fault in the barrel metal which suddenly gave way and caused the barrel around the chamber to split, taking the top of the receiver ring with it.
If there was enough left of the receiver in the case at hand, it might resolve the mystery by determining whether of not the receiver steel had chrystallized. If that is not the case, then looking elsewhere to a possible double charge or excessive lubricant which had migrated to the case neck. Barring those possible explanations, then the blow up must remain a mystery.
