Hello T,
Let's start off by calling things by their proper names and not "thingies":
Bushed Firing Pins - Circular steel fittings, about 1/2 inch in diameter, screwed into the breech face of a gun and through which the firing pins pass. Firing pin bushings allow the convenient replacement of broken firing pins. They also allow the renewal of an older gun where, over the decades, leakage of high-pressure gas from corrosive primers has eroded the breech face around the firing pins. In British: Disk-set strikers.
Good ideas above as to how to proceed.
Genelang, I suppose you mean at 180º not 90. If indeed the holes were at 90º the bushings would be very difficult to extract when stuck.
JC
P.S.: Quote above from
Hallowell & Co. 
