I have a MK 2 target pistol with about 7000 rounds through it with no problems except the firing pin return spring has broken twice. The gun operates fine even when its broken but has anyone seen this before? Thanks Pete
I've not run into that. It sounds like it must be rubbing somewhere. I would clean up anything it touches with a little Dico stainless grade buffing compound (Ace Hardware stores have it and it polishes regular steel and especially hardened carbon steel very well) on a felt bob in a Dremel tool. If you find any hardened or sharp burrs on the rebound spring support, stone them off before polishing. Then get a small bottle of Sprinco Plate+ Silver (the black stuff), clean the spring and ever part it touches with mineral spirits or Bore Scrubber or some such solvent, then soak them all 72 hours in the Sprinco product. It introduces a permanent lube into the steel surfaces.
Thanks Unclenick for without you I wouldn't have gone to the Ruger site to elaborate on the problem and realized I had been putting the rebound spring and rebound spring support in backwards for 4 years and 7000 rounds and broke 2 $1.99 springs without any other problems, I love this pistol.
As long as you didn't put the barrel in backward there was no real danger.
Check that the reversing of the parts didn't peen anything to raise a burr of some kind? If so, same advice on stoning, deburring and polishing. Glad you found the cause of your difficulty.