I think I can rule out the headspace problem as I understand it.

First, the brass was Winchester brass that had been previously fire one time only, and the same rifle. Thus, it was well fire formed to the chamber. It had been annealed before the first and and second loads in my annealing machine. I have great faith that it was neither over or under annealed.

More importantly, I was using a lead bullet (approximately Lyman #2 alloy for hardness), which I had loaded a bit longer than MOA so that they were forced into the rifling. This made the bolt hard to close because the lead was lightly engraved on the first band and nose and the bullets, being tumble lubed, had to negotiate that sticky nose into the rifling. There is no chance that the brass was anywhere but against the bolt face when the primer stuck.

Because the bullet was well engaged in the throat, there is also very little chance, in my mind, that the firing pin could have moved the case forward before detonating the primer. If this was happening, the primer strikes on the prior rounds would be quite light, but they are not.

Perhaps engaging the rifling with the bullet increased the pressures substantially. I have my doubts about this since breech seating procedures that do the same thing to a greater degree are widely practiced in the Schuetzen world where I sometimes hang out.

So, in sum, I think we can rule out headspace as the cause.

I will measure across the threads of the barrel and see what I find.

The remains of the blown round are still in the chamber so trying to fit a piece of brass in there is not possible. I have not tried to extract the brass. BTW, all the previously fired rounds had extracted normally with ease.

I am on the fence about these SEE events. Maybe, maybe not, but several folks have independently informed me about 5744 being a bit "tricky" in that it seems to have produced other unusual and rare events that might be signs of high pressure issues in seemingly normal loads.

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BrentD, (Professor - just for Stan)
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