Has anyone ever seen this problem before (see photo)? It has suddenly developed on a Colt 1911 Mk 4.Series 70.
The loads shot have been commerical ball and minimum target handloads.
The metal is deforming and locking the firing pin from retracting.
Soft steel due to improper heat-treat. Series 70s and Colts built in the mid to late 70s tended to be hit and miss as to quality. Some were as good as I've seen, and others haven't been worth bringing home. Most fell somewhere in- between. The fix is the same as it was in the days before slides were hardened. The center of the breechface machined out and a hardened insert installed.
1911 Tuner: Thanks. Suspected that was the problem. I will contact Colt to see if they will do the repair but expect that since I had Tussey do a reliability job on the ejection port in 1986, Colt may evoke the 'no modification' rule and deny the warranty.
"The metal is deforming and locking the firing pin from retracting." A word of caution. If the firing pin locks in the forward position, your piece will one day go fully automatic! I'd recommend you stop using it and get this problem corrected, ASAP.
What CJR said, though I wouldn't be as concerned about burst fire as firing out of battery. That can be nasty.
Given that the damage was done by primer setback, I'd also have the headspace checked. My bet is that it's excessive.
I would suggest you explain to Colt that you feel this is a safety issue that can inflict significant personal injury ($$$$). This is not a normal "wear problem" but the result of improper heat-treat in the slide that has also increased the headspace. Tussey is a respected 'smith and opening-up/machining the ejection port is not relevant to this safety issue. Over the years, I've found Colt to be reasonable and they will do what is necessary to correct problems like this.
If Colt proves to be uncooperative, Jim Clark Jr. may still make those little off-center firing pin bushings we used to use occasionally when a barrel fitting resulted in a too-low firing pin strike.
But I also believe Colt should take care of it for you.
Talked to Colt's Service Department. Colt's Service Rep. suggested I send it in (it is in box and will be shipped on Monday. FYI the Colt Service Rep (Cindy) was quite professional and gave clear instructions as how to ship it. Am looking forward to their evaluation of the problem.