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Discussion Starter #1
Hi, everyone. I’m looking for some of your thoughts about a light primer strike issue I had today.

I decided to try out the Wolf 18# mainspring in a couple of my guns. One of them, a P227, had a light primer strike; the others (p220, M11A1, (.357 sig), P229) didn’t.

It occurred as I was shooting through a box of Armscor .45ACP while in DA. I reloaded the round and tried to fire it again in DA, but got another light strike, just slightly off of the first. Then I tossed the round.

Also, I installed an Armory Craft flat dual adjustable trigger on the gun. When I got home and was cleaning it up, I noticed it wasn’t resetting after double action dry fire because the pre-travel screw had walked out slightly and was leaving the hammer partially cocked.

I’m guessing it was the trigger, but can’t rule out the spring. I’m not too familiar with Armscor ammo, but I don’t think it’s top shelf stuff. Beggars can’t be choosers.

Like many others, I don’t have a bunch of ammo to troubleshoot with, so I’m wondering what everyone thinks. Thanks.
 

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On some classic Sigs, if too much over travel is removed, the safety lever may not lift the firing pin block plunger high enough to completely clear the firing pin channel. If this happens, the firing pin will hit the plunger, but often continue on after pushing the plunger out of the way. The firing pin will then not have adequate energy to fire the primer - light strikes.

My fix was to make new, "high lift" safety levers. Another fix is to increase the overtravel.

You can feel all this with hammer cocked, hold the hammer back with thumb. Push on the firing pin with a frangible object, Q-tip, chop stick, etc. The, while still holding hammer back, slowly pull the trigger. If the firing pin moves forward, you're good, if it doesn't or moves forward with felt resistance - not good.
 

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If you have fired that ammo in the past and not had issues I would bet on the light springs. If you haven’t used that ammo before reinstall the original springs and see if you have any failures.
 

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good info Bumper!!!

I have had a few light primer strikes on a p365. Was thinking it could be the slide not returning fully to battery but your explanation is better.
 

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Discussion Starter #6
On some classic Sigs, if too much over travel is removed, the safety lever may not lift the firing pin block plunger high enough to completely clear the firing pin channel. If this happens, the firing pin will hit the plunger, but often continue on after pushing the plunger out of the way. The firing pin will then not have adequate energy to fire the primer - light strikes.

My fix was to make new, "high lift" safety levers. Another fix is to increase the overtravel.

You can feel all this with hammer cocked, hold the hammer back with thumb. Push on the firing pin with a frangible object, Q-tip, chop stick, etc. The, while still holding hammer back, slowly pull the trigger. If the firing pin moves forward, you're good, if it doesn't or moves forward with felt resistance - not good.
That’s great advice. Thanks!

Well you have a few variables to deal with. First I would try different ammo. I have 18lb springs in all my guns without issue.
If you have fired that ammo in the past and not had issues I would bet on the light springs. If you haven’t used that ammo before reinstall the original springs and see if you have any failures.
I only had one box of the stuff, and I don’t think I’ll be buying it again (if I can help it). Unfortunately, the light strike gave me the heebie-jeebies. I can’t have that type of stuff happen in DA on a future carry gun. I put the original spring back in and will keep the 18# ones in my other range guns. I suppose if I’m worried about my DA accuracy, I should just shoot more instead of worrying about lightening up the trigger.

Thanks for the feedback!
 

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It happened twice? With the same round? And only that round? Your gun fired all other rounds from that box of ammo. Sounds to me like a bad round and nothing to do with the gun.
 

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good info Bumper!!!

I have had a few light primer strikes on a p365. Was thinking it could be the slide not returning fully to battery but your explanation is better.
Sorry, my advice doesn't necessarily apply to P365's (I haven't worked on them and so don't thoroughly know the mechanism).

As to the 18 lb springs, that is unlikely to be the culprit. I've never had a problem with them. Not saying it couldn't be, but if it is, I'd expect there's other contributing issues. Also, FYI, a spring can be labeled as a given weight, but according to Wolfe Gun Springs (who make the ones Gray Guns sells also), the expected tolerance is plus or minus 1 pound. I made a spring test rig and found that to be the case - then called them to confirm. They test samples from a batch.
 

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Discussion Starter #9
It happened twice? With the same round? And only that round? Your gun fired all other rounds from that box of ammo. Sounds to me like a bad round and nothing to do with the gun.
That’s correct. And both were with a DA trigger pull. Both left indents on the primer and were maybe one mm apart from one another.

If it wasn’t the spring, I was thinking that maybe the pre-travel screw on the trigger was leaving the hammer partially cocked/ not completely decocking and creating a lighter strike.

The gun fired through the rest of the 50rd box and through about 30rds of Federal 230gr FMJ with no issues.

That’s not a very large sample size to determine reliability. I’ve never shot Armscor, but it was about 30% less than the Federal at my LGS.
 

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The gun fired through the rest of the 50rd box and through about 30rds of Federal 230gr FMJ with no issues.

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+1 Swirling Eddy

If the other primer indents are normal, it was most likely that one round.

I'd also recommend a thorough cleaning and lubing on the off chance the slide wasn't going fully into battery.
 
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