Originally Posted by
sabotloader
ronlaughlin..........................Does the shim ring you build go between the base of the bushing and the frame or under the 'o' ring area? In my recent discussion with MD he feels the 'o' ring is used as the headspace device and indicates that the bottom of the firing pin bushing does not seat on the frame................................
The bushing is like a vent liner in that it is threaded, and has a hole in the middle. The head is like a cap screw head that doesn't have a socket, but rather is slotted. Here is a picture posted by the cva lad.
I didn't change anything when i use my washer like shims. I just slipped them over the threads (4 of them 0.005" each) and tightened the bushing into place. I didn't study the situation closely when i had it apart. I was going to take it apart, and take a picture for you today, but i went and did some shooting this afternoon.
I guess what i see is the o-ring makes a seal between metal parts, and there is no metal to metal contact between the head of the bushing and the receiver, even when one uses the shims that i used. Hope this answers your question.