[Bart B.]

FWIW, IMHO there's definately such thing as excessive headspace, for a reloader using rimless bottleneck cases. All it takes is for the reloader to set his die in the press according to instructions provided, full length size some cases, shoot them if a rifle with excessive headspace and the next full length sizing cycle may well have their head clearance enough to let incipient head separation start if it hasn't already. Probably guaranteed to have head separations on the next go around if chamber headspace is near the FIELD gauge limits or past it. That FEILD gauge limit is meant for new cases first time fired, not resized ones. For resized cases, the NO GO limit applies.

And using transparent tape as a head clearance or headspace gauge is akin to measuring groups for accuracy with a rubber ruler. Depending on bolt lug and receiver lug smoothness and lubricity along with the bolt's camming properties, you'll get more than a few thousandths error with that tape. To say nothing of how much a chambered case shoulder will set back by the camming forces on the bolt when closing it on the case head.

If one doesn't understand the mechanics of how this happens, maybe they should not be reloading in the first place.