COAL

[RKG]

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Keep in mind that the longer you seat your bullet out the more pressure you will get in the chamber. It might be best to stick with a conservative COL and find where your nodes are. Once you found the best load then you can start tweaking bullet seating depth.

Not quite. Up to a point -- which is just shy of the bullet touching the lands upon chambering -- lengthening the COAL will actually reduce peak pressure (albeit only slightly). This is so because -- with the same caveat -- lengthening COAL increases combustion chamber volume upon initial ignition.

A pressure spike is possible at the point of lands contact (or beyond that point, which is called "jamming") because doing this spikes the resistance of the bullet to initial movement down the bore, which, in turn, delays the increase in combustion chamber that results from the bullet's movement down the bore.