"...but there is no discernible wear..." Isn't something you'd be able to see.
I'm guessing the M44 is a cock on opening rifle. Very much guessing. Since the thing is going bang on opening, your sear or striker is likely worn. Mind you, the trigger is also adjustable and that
might be too light.
This will help.
http://stevespages.com/pdf/mossberg_44us.pdf