Deer Creek Products, PO Box 246, Waldron, Indiana 46182. (317) 525-6181.
This is a phone number I don't recognize but my dealings with them were from some time agoe and I am fairly certain it is the right folks.
They are good people to deal with. Very helpful and when I was looking, they had more ASM parts than anyone else I could find.
ASM parts are as scarce as hen's teeth and you may find yourself using a different manufacturer's wedge and making it smaller.
VTI Gun Parts is also a source but when I was looking for ASM parts they had screws and not much else. http://www.vtigunparts.com/
and (860) 435-8068. Also very nice folks.
Both of these sources may be able to tell you what wedge is closest if they don't have the OEM.
Others in the group may have some additional suggestions.