Many times the Hunter One-trigger stamping is not in an oval in front of the trigger guard bow; but is stamped on the trigger plate beside the trigger slot inside the guard bow. Also, I don't necessarily think a new trigger plate would be installed if a gun were returned for a retro-fit single trigger. The trigger plates for single and double triggers appear to be the same plate; even down to milled double trigger slots, as the "empty" slot remaining from a single trigger installation is used for the location of the barrel selector switch. I may be wrong; and, if I am, I expect to be corrected by some of the good folks here.