Hammerli Misfires Every Second Round

I recently had my hammer spring replaced and now every second shot, of 18 rounds, misfires. I can reload the misfired round into the magazine and shoot it without additional rounds in the magazine. Additionally, of 2/18 rounds on the first shot the hammer doesn’t cock back or the hammer doesn’t fall after I pull the trigger. 

Before replacing the hammer spring, the pistol would misfire somewhere from 3-6 of 50 rounds in any given position in a sequence of five. 

I’m using CCI SV which has worked for this pistol, historically. What might be causing this? Any insight would be appreciated.

Some quick checks:

- Pull the slide and try the "plop" test for your rounds - they should drop into and out of the chamber without help.

- With a good light, look at the back end of the firing pin - see if it might be mushroomed at all.

- Examine the headspace to see if the top, where the firing pin protrudes, has closed downward at all.

- Look at the orientation and profile of the firing pin tip.

- Tip the muzzle end of the slide down, press and release on the hammer end of the firing pin and check that the tip protrudes and retracts.

- Examine the area around the extractor slot and make sure there are no dings from the extractor hitting beside its slot.

- Examine that no portion of the extractor other than its hook protrudes from the slide.

Ed' has it all, if you changed the Main Spring you need to change the recoil spring. 

You mentioned CCI SV, I have a brick I got and I am very sure it is lousy, other ammos run good. Try another Ammo it could be CCI. 

Last changing the firing pin and cleaning the firing pin channel makes a huge difference on these. 

If your pin mushroomed Cardinal has better ones and if you return pin to Walther they should give you a new one.

Another thing you can try is loading 6 bullets, I usually load a snap cap and see if that helps.

rich.tullo wrote:Another thing you can try is loading 6 bullets, I usually load a snap cap and see if that helps.

I took it back to the range yesterday and continues to fail on the second round, so not sure how using a snap cap helps anything

rich.tullo wrote:Ed' has it all, if you changed the Main Spring you need to change the recoil spring. 

You mentioned CCI SV, I have a brick I got and I am very sure it is lousy, other ammos run good. Try another Ammo it could be CCI. 

Last changing the firing pin and cleaning the firing pin channel makes a huge difference on these. 

If your pin mushroomed Cardinal has better ones and if you return pin to Walther they should give you a new one.

I shot some Eley target and Eley club yesterday, so I can leave ammo out of the equation. I’ll take a look at the firing pin and take some of Ed’s suggestions today.