I've had a 512 Sport master for years ,got it from my Father n Law in the 1990's . It always jammed and basically a single shot.
Set in the back of the safe until last week I thought I would test it see what could be done.
Still jammed every shot , so I started doing research .Found several problems but no smoking gun .
Decided to disassemble and found the culprit ,dried hard varnished oil from years ago between carrier and cartridge stop.
After an acetone soak and burnish with scotchbright parts are smooth and clean .
Light CLP and back together they went.
There is an adjustment screw that these parts pivot on which was factory staked.
Tighten all the way and back off until carrier clicks from spring tension.
The tension on this screw is critical how the feed works . once confirmed it feeds every rounds from tube.
Stake the slot with a punch to move metal into screw slot.
I also found a factory burr on the tube feed lip edge.After good brush scrubbing everything worked as intended.
Found the mag tube hit forend before action seated so careful radius scrapper relieved that .
First target test for function ,adjust elevation on second target .
Final group at 25 yards.
Decent trigger pull on these and excellent fine sight picture .
With target ammo this will shoot all X's every time.