jonsorrick: Sounds like the pistol might be in need of a new recoil spring. Second most likely culprit would be a bad magazine. You might want to get both.
Stick with 230 gr FMJ ("Hardball") initially. The gun should have no problems with that load. If everything is functioning with hardball, try something like Hydrashock .45 ACP. A lot of weapons from that timeframe were not throated for reliable feeding of hollowpoints. If you find something that appears to work, test fire at a minimum of 40-50 rounds of your chosen load.
Try ordering online from Numrich Arms:
http://www.e-gunparts.com/productsch...2010zPD%20AUTO
Item # 128670, Recoil Spring, Part #40 in the above schematic parts diagram for Star PD. $5.35
http://www.e-gunparts.com/product.as...ductSKU=128670
Glad you have a "third generation" firearm. Nothing wrong with the PD...it was a trend setter back in the '70s. I owned a Star BKM 9mm back then; also a good gun.
Hope this helps.