Note case on the left has much more metal in the area in the bottom than does the case on the right. The left case is a M193 case and the right is a commercial case. The case on the left is a much stronger design.
The below is a sectioned barrel with 20,000 rounds on it. Note there is a area of the case that is unsupported, thus the need for a thicker head.
This is why when I barrel my bolt guns I make sure there is min movement in the bolt when pushed forward as I want all the support from the chamber wall I can get. You will probably notice on some rifles with the striker down you can push the bolt forward quite a bit, that means you have unsupported case head and with commercial cases being lighter than MILSPEC you can have head failure.
The below is a sectioned barrel with 20,000 rounds on it. Note there is a area of the case that is unsupported, thus the need for a thicker head.
This is why when I barrel my bolt guns I make sure there is min movement in the bolt when pushed forward as I want all the support from the chamber wall I can get. You will probably notice on some rifles with the striker down you can push the bolt forward quite a bit, that means you have unsupported case head and with commercial cases being lighter than MILSPEC you can have head failure.
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