Originally Posted by
Ballistics in Scotland
I thought someone made and then rather needlessly deleted a query about my last sentence. It may have been for the mention of a .208-sized case head, which I have now corrected to .308-sized. For the rest, rechambering to an Improved case shape can in some rifles produce problems with how the rounds stack and feed in the magazine, but that doesn't apply when you don't have a magazine.
I can tell you the bolt thrust on my .40-82 Winchester 1886 Winchester, with assertive but moderate smokeless loads. It exerts no thrust whatever, since the primers are extruded to the limit of its considerable rbut not excessive headspace, and the case doesn't move back to push them in again or mushroom them. The case body is held to the amber by gas pressure, and the case head is held to the body by the strength of the brass. The modern brass case had pretty much the size and work-hardening of a quarter-inch brass rod. Similarly Ackley found that a .3xe 0-30 Improved could be fired with his Winchester 94 locking lug removed.
The reason we can't dispense with bolts and breechblocks, when they are such a nuisance, is that chambers can be wet or oily, and people do reload cases until they get head separations, and the strength of brass becomes none whatever. Rifle design normally allows for the worst, but I do believe H&R, in not going for the magnum case head, knew what they were doing.