Yeah that happened to mine so many times I actually got rid of the
C-ring. If you look in the manual you will see there are 5 pieces to that
1. Guide rod
2. Inner Spring
3. Outer Spring
4. (C ring)
5. Retaining Ring
You can reassemble it without the C-ring if you have the
Place the Retaining Ring "washer" in the slide with recess facing forward.
Slide both springs on the guide rod.
Insert guide rod and springs into slide.
This can sometimes be difficult due to the slot cut out for the C ring.
Take your time and be sure the everything is aligned.
DON'T FORCE IT. It should go on with minimal effort.
P.S. the C-ring is not going to effect the function of the gun. It is simply to
aid in reassembly. (As far as I can tell.)