i have this mental image that with a normal sized case (say, 0.002 headspace) the cartridge gets driven ahead before ignition and thus mostly centers itself on the chamber shoulder, aiding in bullet alignment (assuming runout has been controlled).
To begin, we have no idea about relative bullet centering of crooked ammo. It's an abstract. So jamming low angle shoulders into a center could be the very worst situation for centering of bullets -of 1 or 2 rounds in a group(while good for the others).
It's my contention that any amplitude of this affect would be tied to clearances/chambered tensions with it.
It passes tests logically, I know of nothing else that does.
But, I have not directly tested this, as it's not as easy to do so as it seems.
To test this theory means planning and acting to cause a broken condition. Producing and shooting high runout ammo in a chamber(entire chamber) tight enough to interfere with tension free chambering of
that ammo. Then comparing results with normal straight ammo prior produced in
that chamber. That's the only valid test.
Problem is, a tight chamber like that produces very very straight cases. How will I produce high runout ammo with that chamber?
Forcing seated bullets off center is only one runout type. To make realistic bananas for the test, takes heavy FL sizing of cases with thickness variance. Out of a tight chamber, this would take a good number of firing/sizing cycles.
It's hard to produce crooked ammo without clearances to do so. Efficiently doing it would mean testing with a cartridge so poorly designed that producing straight ammo with it is rare(like a 30-06). Then that same cartridge would have to shoot well enough to measure results in this narrow test.
Much of that goes into things I haven't and wouldn't ever do. Too much effort.
Would be interested in efforts/results from somebody else doing it.