Ruger P-89 misfires


December 3, 2012, 07:51 PM
I have a Ruger P89 DC 9mm I need advice for.

I purchased this gun used many years ago. A few months ago I decided to start shooting it again. On the first session of 50 rounds I had some failures to fire with the first hammer strike. I disassembled the gun, cleaned out the sticky residue from dried WD-40, installed new firing pin spring, re-oiled lightly with CLP and reassembled it.

The gun has functioned fine on the next two sessions of 50 rounds each for a total of 100 rounds. Today I had a number of failures to fire on the first hammer strike when fired in double action. All of the rounds fired on the second hammer strike and all of the rounds I shoot in single action mode fired the first time.

I tested a magazine of 15 rounds all double action with one failure to fire. Since I am nursing a sore shoulder I then fired six rounds weak hand double action with one failure to fire.

The ammo is my reloads using CCI primers. My first thought was I failed to seat the primers all the way. However since the ammo is randomly boxed from a batch of 500 rounds I reloaded, the last 100 rounds fired fine and all of them fired fine in single action mode I discount this basic of reloading mistake.

I do not know if the hammer spring is factory original.

Please spare me the “use a softer primer” comments. I know CCI primers are hard which is why I like to test them in my SD/HD guns which I demand go bang everytime.


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December 3, 2012, 08:14 PM
Used gun when you got it = At least a used spring.
And possibly a coil-clipped one when you got it.

Replace the hammer spring with a new one from Ruger or Brownells.

If that doesn't fix it, at least you are starting from behind the goal line.


December 3, 2012, 10:07 PM
Thanks. I suspected the hammer spring but was wondering why the double action hits are light and single action hits are stronger. I didn't know if I needed to replace the firing pin also.

Jim K
December 3, 2012, 11:37 PM
I think rcmodel has the answer; I doubt you need to replace the firing pin. The reason DA gives more misfires is that the hammer doesn't come back as far as in SA firing and so doesn't build up as much momentum before it strikes the firing pin.


December 4, 2012, 09:00 AM
Thanks for the advice. It all makes sense. I should have also replaced the hammer spring when I replaced the firing pin spring. As sticky and gunky the firing pin spring/channel was I thought I cured the problem.

Thanks again. I'll order a new hammer spring today.

p.s. I went whole hog and ordered a new recoil spring as well. I figure I might as well update all of the old lady

December 4, 2012, 10:05 AM
I would say hammer spring, primer depth and primer hardness. I like CCI primers too though. I just used up the last of them I had. The P series by Ruger are one of the best pistols for the money on the market. HANDS DOWN!

December 4, 2012, 04:23 PM
Before you get any further into the gun, try some factory loads. If they function the gun normally, the problem may well be in the reloads.

December 4, 2012, 07:22 PM
Naw. I'm pretty much convinced the problem is the hammer spring is tired. After all the ole gal is 30 years old. Spring replacement is basic maintenance for semi-autos. I just a little embarassed I didn't think of replacing it when I replaced the firing pin spring.

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