I measured a '98 Krag and I get .545 from backside of lug to rim of bolt face. I don't have feeler gauges to measure the gap behind the safety lug (and I'm not running back to the shop to get them!) but it sure looks like between .010 and .020".

"You can lead a man to logic, but you cannot make him think." Joe Harz
"Always certain, often right." Keith McCafferty