A PA32 PLT DSNDED BELOW MDA ON APCH TO HXD.

Narrative

FLYING THE LOC 21 APCH TO HXD. BROKEN LAYER OF CLOUDS AT 400-500 FT MSL. THROUGH A HOLE IN THE CLOUD DECK; MADE VISUAL CONTACT WITH THE APCH END OF THE RWY ENVIRONMENT AND BEGAN DSCNT BELOW MDA. SUBSEQUENTLY LOST SIGHT OF THE RWY ENVIRONMENT DUE TO LOW CLOUDS. INITIATED MISSED APCH AND DIVERTED TO DIFFERENT ARPT WITH VFR CONDITIONS. NOTICED DURING THE MISSED APCH THAT THE ALTIMETER HAD NOT BEEN SET TO THE DEST FIELD SETTING. RPTED CEILINGS (VIA ATIS) WERE 400 FT (MDA WAS 480 FT) YET THE CONDITIONS WERE EXTREMELY LOCALIZED. PASSED OVER THE NEARBY (IE; LESS THAN 10 MI) BEAUFORT MARINE AIR BASE WAS VFR (WITH CLR SKIES). GIVEN THE FACT THAT CEILINGS WERE RPTED OK (AROUND 3 MI); WINDS WERE CALM; AND THERE WASN'T ANY OTHER ADVERSE WX SEEMED REASONABLE TO SHOOT THE APCH. BECAUSE I WAS MENTALLY ANTICIPATING A MISSED APCH; AND THERE WAS OTHER IFR TFC IN THE AREA FOR THE SAME APCH AT HXD; I FLEW THE APCH FASTER THAN NORMAL (ESPECIALLY WHEN NEARING THE ARPT). GIVEN A SLOWER APCH SPD I WOULD HAVE HAD A STEEPER DSCNT GRADIENT; AND PERHAPS BEEN ABLE TO GET BELOW THE CLOUD DECK BEFORE LOSING SIGHT OF THE RWY. ALSO; DISTR BY UNEXPECTED RADAR VECTORS (FOR SPACING DUE TO OTHER IFR TFC); I FAILED TO CHANGE TO THE LCL ALTIMETER SETTING; AND THE FACT THAT NEARBY WX WAS VFR ALSO CONTRIBUTED TO A SENSE OF COMPLACENCY.