Broken Hammer

I don’t know how or when this happened but the gun has probably fired 100,000 rounds so that is a decent run for the one part. The replacement, from a different manufacturer, is on the left. The original is on the right.



12 thoughts on “Broken Hammer

    • I’m sure it improved the lock time. But that was at the expense of frequent light strikes and failures to fire.

  1. That’s the most positive half-cock notch I’ve ever seen. Also, I’ve never known anyone to use that notch – I guess it’s irrelevant. Just interesting, sorta.

  2. Metallurgy sometimes fails. May have been from a bad batch of steel. Such a failure is unusual. Hammers move short distance often but the amount of force exerted on them by falling against a firing pin isn’t all that great.

  3. Interesting place for a failure. I wouldn’t have expected sufficient stresses to be concentrated at the thumb knurling tab, although when the hammer contacts the firing pin stop on a 1911 it’s a rather hard stop, so it’s seen 100K of those “hard stops.” And, carried properly – Condition 1 – the hammer is raised and may wind up getting struck often by whatever the gun bumps against. (I’m assuming it’s from a Daily Carry & Regular Competition gun).

    From the pic it looks like the original was a machined part, not MIM, and machined parts are supposed to be “So Much More Betterer than that “MIM $@&%.” At least when it failed it didn’t shut the gun down completely.

    How many years did it take to cycle those 100K times? Might be useful to know for replacement part maintenance scheduling.

    • It was a daily carry, practice, and competition gun for 17+ years. Then, with a .22 caliber upper, a practice and competition gun for eight years.

      Yes, always carried with the hammer cocked.

  4. It looks like the pistol was dropped with the hammer down and it landed on the hammer loop. It doesn’t seem like an operational failure unless it had been dropped in the past and the fracture was not noticed then over time it gave way.

    That half cock notch looks like it belongs on a lever action rifle. I never have used the half cock on a 1911 but on a lever gun it’s the standard position for field carry. It seems more secure that the trigger block.

    Best regards,


    • I keep thinking dropped too. But I only remember it being dropped once, on gravel with the hammer cocked, about 20 years ago.

  5. It would be interesting to get microphotographs of both fracture surfaces. If it was a fatigue fracture one side should show it.

  6. I’d say the original fracture was at the knurled end, and the bottom eventually broke due to flex. I suspect that with so little mass, the thumb part got thru tempered to a hardness it didn’t need, making it too brittle. Shame you don’t have the missing piece for examination.

    • Makes sense, the knurling process would put a nice initiator crack to get the ball rolling all those years ago.

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