TargetTalk

I'm helping coach the MIT collegiate team, and one of our shooters has been getting frequent misfires with a Hammerli 150. The cartridges that fail to fire have only a very light firing pin mark. One of the other coaches took it apart far enough to verify that the firing pin/striker was intact, and he cleaned out the firing pin channel. Unfortunately, that didn't seem to help.

The most likely remaining culprit I can think of is a weak striker spring. It's possible the pistol was left cocked for an extended period of time in the past. Is there anything else we should check before trying to track down a new spring?

Thanks!

The TOZ FPs have a very similar design and have poor quality springs.

Replacing the striker spring cured the problem in a couple of TOZ here, including my own.

PM me and I'll fix you up with a spring that MAY work.

Minor(?) correction: It turns out it's a 160, and not a 150. The spring for the 150 is #042070, but it looks like Hammerli revamped their numbering system for the 160, where it is called out as a 1.052.200. I suspect they are probably interchangeable.

Someone else suggested cutting one from a Wolff spring kit. I have a pretty large selection of Wolff springs & spring kits from Brownells. Given a new one as a reference, or a bit of cut and try, I'm sure I can come up with an equivalent that would be cheap. If I come up with a easily manufactured solution, I'll be sure to post it.

The team has a full match schedule at the moment and changing ammo has apparently helped a little. I'll check with the student tomorrow and see how pressing the repair is. I've never had a 160 apart, but a couple of the other coaches have, and I may want to coordinate with them rather than risk screwing it up before the next match.

If someone has a spare spring they could measure, I can make up some to try. I'd need the outer diameter, length & ideally the wire diameter. If you are feeling generous, the number of turns should allow me to come up with a very close match.

Thanks!

Sir,
Some years ago, I bought 5 spare 150/152 firing pin springs. They have never been put into a gun. They measure .049" wire diameter, .198" OD, and OALs of 1.275, 1.285", 1.293, 1.300", and 1.305"; both ends are ground square. Hope this helps.
Paul Ha.

Sorry, forgot to mention......everyone of them has the same number of 17 turns from end to end. Paul Ha.

Perfect! I'll compare this with my spring stock collection, and can hopefully come up with a good substitute.

Thank you!

Might I suggest using an actual Hammerli firing pin spring?
They are very high quality and will last a long time so long as the gun is not stored cocked. That spring is under quite a bit of tension and is engineered to last under that application.
www.larrysguns.com sells them. They are not expensive.

Please let us know if your alternative works out to your satisfaction.

Best Regards,
Jim

In theory, we have one on order, but because of the storms, we may not see it until after the next match.

Although they should last a long time, they are $9 each from Larry's. Depending on the length of my spring stock, I can make at least a half dozen for next to nothing if I can get a good match to the dimensions Paul Ha provided.

I'm really interested in how this works out. If you come up with a suitable spring, please post whatever pertinent information you can.

By the way, how are things going at MIT? I was very impressed with the pistol program there.

Best Regards,
Jim

Yeah, the spring will be $9 and the postage $8.

Just take trigger return spring from a S&W revolver and pop it in. I bet it will work.

Rover wrote:Yeah, the spring will be $9 and the postage $8.

Just take trigger return spring from a S&W revolver and pop it in. I bet it will work.

I'll have to find my K38 parts bin & see if I have one. If so, I'll check how it matches up with the dimensions we've got.

6string wrote:I'm really interested in how this works out. If you come up with a suitable spring, please post whatever pertinent information you can.

Will do.

By the way, how are things going at MIT? I was very impressed with the pistol program there.

We're muddling along. Everyone is still trying to adjust to the demotion from a varsity team to "club sport" status two years ago. Before, the team had a paid coach & moderate funding from the university. Now, we are running mostly on donations and the coaching is done by volunteers. Will Hart retired last August after coaching the team for many successful years. Because of the change of the team status, his last year as Coach was unpaid, while he continued as Range Master & PE instructor. MIT has hired a new person to take over those two jobs, but he doesn't have a competitive shooting background. He has expressed an interest in getting involved with the team, but only after he's fully comfortable with his other duties.

I am one of four volunteer assistant coaches from the ranks of alumni & the faculty pistol & rifle club. We run the practices during the week. Will (thank goodness) still coaches on many weekends, and has been invaluable helping out with matches, especially the away matches. A lot of credit also goes to the team members, who have really done a super job of taking over a lot of administrative tasks, as well as helping to train & coach new shooters.

The long term plan is to set up an endowment so we can fund a part time coach as well as the general operating expenses. We also need to try to get some corporate sponsors. Please PM me if you have just won the lottery and would like to help out.

Back on topic: I managed to get a 160 spring from Larry's through the blizzards. It's VERY different from the Hammerli 150 spring.

Overall length is 1.633 inches, outer diameter is 0.205 inches, with 21 turns of 0.040 inch diameter wire.

It's a pretty beefy spring. Without even looking, it's also much bigger than a S&W revolver rebound spring. I haven't had time to go through my spring assortments to find a good match for the future, but I'll try to do that tomorrow & report back.

Hi,
Thanks for the updated information. I'm not too surprised that the 150 and 160 springs are so different given how differently the two perform in actual use. I am surprised that I hadn't already noticed since I've owned and used both the 160 and 152.
My personal experience has been that the changes made to the 160 in regard to the breech block design, chamber dimensions, and the manner for cocking the pistol were all excellent improvements. In fact, I sold my 152 shortly after acquiring my 160. I found the 152 was more prone to light striking when the spring got tired. Also, the cocking effort, loaded round seating effort, and even case extraction, were all much harder than with the 160.
By the way, your observations on the current status at MIT were most helpful. I teach at a small college and have been talking to various individuals about adding some pistol shooting to the other on campus shooting activities, which currently are service rifle oriented and affiliated with the military science dept.
Thanks,
Jim

I looked through my extensive spring collection, and I'm glad I ordered a "real" one. I found one spring in a Brownell's kit (Kit #3 ID-12) that is very close, but probably not close enough. It has almost exactly the same winding pitch, and the same outer diameter. The problem is that the wire is 0.036" in diameter, versus 0.040" for the Hammerli spring.

If I remember my mechanics correctly, the resistance to deflection of a round rod goes as the 4th power of the diameter. That means that the Hammerli spring is roughly one and a half times as stiff as one from the Brownell's kit would be. The spring could be made slightly longer to compensate, but probably not enough to make up the difference.

I'll be curious to examine the old spring when we remove it. Now that we know how long a new one is, it will be easy to tell if the old one took a "set" by being left compressed for too long.

The pistol has continued to have intermittent misfires. I took the breech block home, and this afternoon I finally had time to swap out the old spring. Contrary to my expectations, the old spring was NOT overly compressed. It was within a 32nd of an inch of being the same length as the new one. However, it did have a bit of a kink in it that might have prevented it from firing with full force.

I cleaned everything, and found no dirt particles that could have been blocking the firing pin. Basically, I found no clear culprit for the misfires. All I can do at this point is reinstall the breech block & cross my fingers.

Just today I joined this forum and noticed the exact same light strike issue I once did have, with my Hammerli 150. I too suspected the firing pin spring and replaced it and also added a NIB firing pin. Light strikes continued.
I was lucky enough to find a gunsmith in Calgary that once worked for Hammerli in Switzerland. He resolved this problem forthwith. My after market grips (Morini) required a different length to the original factory grip screws. He shortened the problematic grip screws accordingly. Viola! No more light strikes.

sorry for such a tardy responce