Grabbed my .25 Marauder for a back deck few rounds. Bolt handle was hard to open. It was the bolt lug that had loosened.....easy fix and if it happens again I might put a micro dab of blue locktite on it.
This same thing happened to 2000 era Benjamin Sheridan rifles when they started using LARGER hex bolt heads for locking lugs. Opening contact surfaces tend to untorque the bolt and it begins to hit the cover plate/cam plate. Easy fix but if forced without fix will do some damage.
If not the screw in bolt, the screw in hammer.
keep em snug or degrease hole/threads and Loc em with a drop of BLUE as stated.