It doesn't make sense that Sinclair would suggest an extreme clearance from mouth to chamber end.
Why not? It's the lawyer's game that make's them word thing's as they are. I'm not saying all, but chances are you will not even reach that -.024" length with a factory chamber. This is just a conclusion I've came to with my limited experence. I'm .039" from my chamber's max after I've uniformed new Lapua brass. That is why I like the gauge, keeps me from trimming brass to saami specs, that does not need to be trimmed.
Actully, per instruction's read;
WARNING
Excessive case length will cause dangerous chamber pressure's resulting in personal injury. We do not recommend increasing case length beyond published saami specifcation's. DO SO AT YOUR OWN RISK! If you do increase your case length, maintain the case length so that it is a minimum of .024" shorter then the chamber length.