Fast14riot
Gold $$ Contributor
That looks more like a clearance cut for the M16 extractor.
I went back and read up on Ackley and the early Springfields with improper heat treatment and I'm going with your number 2..... JohnMy thoughts-
1.Defective brass failed?
The hot gas went thru the M16 extractor cut.
The vented gas split the receiver?
OR
2. Did the receiver fail first, because of improper heat treating?
Then the case head moved off the bolt face and case head ruptured?
I think #1
Best part, no one was injured.
