I just thought Id share this with you guys. There have been 2 revisions in the bolt/buffer design of the Sig 522 since it came out. There were early reports of people losing E-clips and here are the design revisions that fixed the problems. BOLT Early 522's came with a bolt that has black coating on the outside of it. This bolt design has a cut out notch where the guide rod slips into and then is E-clip'd to the bolt. The newer bolt is all "silver" and has no black coating on the outside. It also does not have a notch where the guide rod attaches. Now it just has a solid hole for the guide rod to go through and then be E-clip'd to the bolt. GUIDE ROD The original guide rod has one end that is tapered. This made it very easy for the E-clip to fall off the end with the taper. The new guide rod has no taper and is the same thickness from end to end. This eliminates the possibility of the E-clip just falling off. The E-clips fit very securely to the new guide rod. Please remember to make sure that the bolt is not locked back when field stripping the rifle. This was the cause of many people losing the E-clips. The bolt would be locked back and they would open the halves and the rear E-clip, buffer, and spring would shoot out. This was mostly caused by the tapered guide rod which has since been re-designed. But to make sure it doesnt happen to you, just make sure the bolt is not locked back when field stripping. If you have one of the earlier versions of either the Bolt (black coated version), or the guide rod (tapered version) just give Sig CS a call and they will send you replacement parts free of charge. I hope this helped!