Funny, I have just had to make up a set this week. Tried the usual suppliers used for spares but no luck. The parts comprise of a small washer, spring, a small wire ring, a short plastic tube, and the main plastic body. The wire ring is the part that latches on to the lug on the barrel. Looks like you have broken parts of the tube and main body. Here is a pic of the main part, I had to make mine from Delrin. I can do a drawing of how it all goes together if you want.
Baz
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