I will give this a try but I am not technically inclined so I may just confuse you more.
A swipe occurs when the bolt tries to turn and unlock before the pressure has dropped sufficiently for the case to release its grip on the chamber.
This can be a high pressure issue or a timing issue. Timing issues seem to occur more often in carbine or sometimes midlength rifles.
Timing issues occur when the peak pressure is not excessive but the pressure arriving at the bolt occurs too early in the progressive ignition sequence.
Anyway feel free to correct me if I am wrong!
Greg
