[ithacaartist]

While checking for relative ammo power, I suggest using the masking tape method. One applies some masking tape across the area on the back end of the frame that the "duckbill" on the rear toggle has probably already left some marks in the frame's finish. You'll be able to tell if your ammo is on the under-powered end of things when there is no contact with the tape at all. Rounds that are too powerful would really chop the tape up--a warning sign that there's excessive energy in the action, and things are bottoming out. If the latter is the case, put in a stronger spring (as Richard advises well to have on hand), because constantly pressing the action to/beyond its limits is a significant factor in breaking stuff!