Light Primer Strikes on New Build

[Michael303]

I just got my new (first) build to the point that I could take it over to the range for a test fire.  It ran great except for an occasional light primer strike so I'm looking for some feedback on what it could be.

 

It's a Jem/Cheeley build with mostly EGW internals and Wolff springs.  The main spring is 17 lbs, firing pin spring is Standard Power, extended firing pin, and the primers were CCI.

 

I don't have a heavier main spring to try but I'm going to order one.  I've searched the forum and it seems like lots of people have no problem running 17 lbs and some even lower.

 

Any feedback is appreciated.

 

 

[CHA-LEE]

If everything else is setup correctly, a 17lb hammer spring and an extended Fire Pin should set off any hardness primer. There is likely some other issue that is either keeping the hammer from hitting the back of the firing pin squarely, such as the lower barrel lugs not cut back far enough and the slide is sitting too far back compared to the hammer strike angle. Or the barrel lock up height is not right and the firing pin is hitting the outer edge instead of the middle. Look at the fired brass, is the primer strike in the middle or biased to one side? With the hammer decocked and resting against the back of the firing pin stop, what part of the hammer is touching the back of the firing pin stop or firing pin? The hammer should be touching the back of the firing pin long before it bottoms out on the back of the firing pin stop.

 

I can take a look at it and tell you want I see if you want.

[ltdmstr]

Offset firing pin strikes shouldn't pose a problem unless they are way off toward the edge.  It's fairly common to not be exactly centered, particularly with a custom build and higher lockup on the barrel.  I would check the overtravel screw on the trigger and maybe back it out a bit to see if that makes a difference.  Also, check the firing pin hole to make sure there's not a burr or something in there.

[raz-0]

OK, I'm going to be that guy that reminds you to check the stupid obvious stuff. Have you verified there's nothing in the firing pin channel that shouldn't be there? 

[Michael303]

1 hour ago, CHA-LEE said:

If everything else is setup correctly, a 17lb hammer spring and an extended Fire Pin should set off any hardness primer. There is likely some other issue that is either keeping the hammer from hitting the back of the firing pin squarely, such as the lower barrel lugs not cut back far enough and the slide is sitting too far back compared to the hammer strike angle. Or the barrel lock up height is not right and the firing pin is hitting the outer edge instead of the middle. Look at the fired brass, is the primer strike in the middle or biased to one side? With the hammer decocked and resting against the back of the firing pin stop, what part of the hammer is touching the back of the firing pin stop or firing pin? The hammer should be touching the back of the firing pin long before it bottoms out on the back of the firing pin stop.

 

I can take a look at it and tell you want I see if you want.

I'll bring it with me Monday night and you can let me know how mediocre it is.  

 

I looked at the hammer angle and the early wear on the firing pin stop seems to indicate the hammer is striking slightly past vertical.  

 

Unfortunately I wasn't smart enough to bring home or photograph any of the brass from my test session.  I don't remember the primer strikes being significantly off center but they did look a bit light.

 

57 minutes ago, ltdmstr said:

Offset firing pin strikes shouldn't pose a problem unless they are way off toward the edge.  It's fairly common to not be exactly centered, particularly with a custom build and higher lockup on the barrel.  I would check the overtravel screw on the trigger and maybe back it out a bit to see if that makes a difference.  Also, check the firing pin hole to make sure there's not a burr or something in there.

Thanks, I'll take a look at both of those items.

 

22 minutes ago, raz-0 said:

OK, I'm going to be that guy that reminds you to check the stupid obvious stuff. Have you verified there's nothing in the firing pin channel that shouldn't be there? 

That's ok because I'm the guy that would miss something obvious.  I did blow it out and clean it out with a cotton swab.  When I push the firing pin manually it doesn't feel like it's dragging to me.  

[Squirrel45]

Not to sound like a smart donkey but the primers are fully seated? I know I have this issue from time to time from me being lazy on the push stroke. 

[Michael303]

25 minutes ago, Squirrel45 said:

Not to sound like a smart donkey but the primers are fully seated? I know I have this issue from time to time from me being lazy on the push stroke. 

Thanks for the feedback.  I just checked from the stock I'm shooting and they look good.  I'm on an 1100 and it primes on the down stroke so it's hard to short stroke it.

[Braxton1]

1 hour ago, Michael303 said:

Thanks for the feedback.  I just checked from the stock I'm shooting and they look good.  I'm on an 1100 and it primes on the down stroke so it's hard to short stroke it.

 

You are right; it is quite difficult to short-stroke a 1050/1100, but it easy to have the primer depth setting slightly off.

 

The way that I confirm that my 1050 is still right is to:

 

     - seat a primer on either my 550, 650, or a hand primer.

     - measure the depth that it is fully-seated (for this example, let's say it's "two thou below flush".

     - de-prime that case and put it in my 1050.

     - seat a new primer and measure the depth of that one.

 

If it's the same measurement, the world is happy.

 

It's important to use the same case because I've found a slight variance between primer pocket depths among the various manufacturers.

 

[raz-0]

4 hours ago, Michael303 said:

That's ok because I'm the guy that would miss something obvious.  I did blow it out and clean it out with a cotton swab.  When I push the firing pin manually it doesn't feel like it's dragging to me.  

 

2 hours ago, Michael303 said:

Thanks for the feedback.  I just checked from the stock I'm shooting and they look good.  I'm on an 1100 and it primes on the down stroke so it's hard to short stroke it.

 

OK, have you tried the pencil test?

[ltdmstr]

37 minutes ago, raz-0 said:

OK, have you tried the pencil test?

 

I thought that was for chicks.

[Michael303]

2 hours ago, raz-0 said:

 

 

OK, have you tried the pencil test?

Can you give me an explainer?  I've never heard of it. 

[Postal Bob]

Have you checked that the firing pin spring is inserted in the correct direction? If reversed, it can cause problems not allowing the firing pin to travel it's full distance.

Edited March 18, 2022 by Postal Bob

[konkapot]

Pencil test is taking the unloaded weapon, cocking the hammer, and placing a pencil in the barrel. Press the trigger and, hopefully, the pencil goes flying up into the air. 

 

Eraser end pointing down. 

 

It's a down and dirty  way to ensure your firing pin is doing what it's supposed to do. 

[Michael303]

4 hours ago, Postal Bob said:

Have you checked that the firing pin spring is inserted in the correct direction? If reversed, it can cause problems not allowing the firing pin to travel it's full distance.

Yes, tight end to the back.  Thanks.

 

2 hours ago, konkapot said:

Pencil test is taking the unloaded weapon, cocking the hammer, and placing a pencil in the barrel. Press the trigger and, hopefully, the pencil goes flying up into the air. 

 

Eraser end pointing down. 

 

It's a down and dirty  way to ensure your firing pin is doing what it's supposed to do. 

Ok, gotcha.  I did assemble the pistol without the barrel to confirm the pin is coming through and it did seem to be going to full depth.  I'll give the pencil test a go to confirm for science though.  Thanks.

[Michael303]

I thought I'd follow up on this one more time to update on what I've tried and see if anyone had some further insight.

 

I went to the range this weekend and tried some factory ammo and some of my reloads with primers set deeper (8-10 thou) than my previous batch without much luck.  The factory ammo (Speer) actually gave me 4 out of 22 light strikes so it's not looking like my amateur reloads are the problem.  I've put thousands of my current load (3.3g N320 under 147g, CCI primers) through my Glocks with a 4lb striker spring without a single light strike.

 

I did play with the pencil test quite a bit and found the 17 and 19 lb main springs will shoot a pencil out of the barrel, both shoot it noticeably shorter than the Glocks with a 4lb striker spring.  

 

I backed out the overtravel screw all the way to eliminate that as a possible issue.

 

Below are a couple pics of some primers, including some of the failures to ignite that were shot with the 17 lb main spring.  To me they look light, particularly the failures, but I'm certainly no expert.  On another forum a few guys with more experienced than I seemed to be concerned that the primers were flowing and causing the firing pin tip to build up metal fragments and cause drag.  Again, I've been using this load in my Glocks without issue and I'm not seeing anything on the firing pin or feeling any drag when I articulate the pin by hand so it doesn't jump out as the obvious cause.

 

I did swap out the 17 lb main spring for a 19 and ran through about 120 rounds (reloads and Speer) without a single issue though.  The consensus seems to be that the 17 lb should be enough, and some even use 15 lbs, so my concern is the 19 lb could just be masking an issue.  

 

 

Edited March 28, 2022 by Michael303
Formating

[CHA-LEE]

Is this with the extended firing pin or still the original one?

[Michael303]

2 hours ago, CHA-LEE said:

Is this with the extended firing pin or still the original one?

This is still the original. The extended is "out for delivery" as I write this. 

[zzt]

Check the firing pin stop.  It may be the back of the firing pin is rubbing against it.

[troupe]

Do realize that just because the package may have said 17lb spring, it could have been a 15lb spring. I have seen it happen.  Sounds like something may be dragging. CCI is some of the hardest primers going also.

[Don_B]

One more question. Did you cut the chamber in the barrel? Is it possible it had excessive headspace?

Just a thought. 

[Michael303]

On 3/31/2022 at 4:24 PM, zzt said:

Check the firing pin stop.  It may be the back of the firing pin is rubbing against it.

Thanks.  I'll double check this.

 

On 4/1/2022 at 9:42 AM, troupe said:

Do realize that just because the package may have said 17lb spring, it could have been a 15lb spring. I have seen it happen.  Sounds like something may be dragging. CCI is some of the hardest primers going also.

I actually took delivery of a spring pull gauge since I started this thread.  I haven't had the opportunity to measure the main spring yet but I'll report back if it's out of spec.  Thanks.

 

6 hours ago, Don_B said:

One more question. Did you cut the chamber in the barrel? Is it possible it had excessive headspace?

Just a thought. 

When I finish reamed it I did have a chamber gauge on hand so it's within SAAMI spec as far as I know.

[Michael303]

I got a chance last night to test a new extended firing pin briefly and went through about 60 rounds without an issue.  I mistakenly assumed that the "O/S" in the EGW O/S Firing Pin that I originally put in the gun meant it was oversized or extended but that wasn't the case.  The new Dawson is significantly longer.

[Michael303]

On 4/1/2022 at 9:42 AM, troupe said:

Do realize that just because the package may have said 17lb spring, it could have been a 15lb spring. I have seen it happen.  Sounds like something may be dragging. CCI is some of the hardest primers going also.

 

To follow up on this, I couldn't find the compressed length to measure the main spring at and the gauge I bought only has a marking for measuring government length recoil springs.  I do have 15 and 19 lb Wolff main springs though and they both measure to the claimed weight at about the same length. 

 

The spring that came in the EGW ignition kit that's in this gun is stated to be 17 lbs but measures at 13 lbs, maybe 14 if I'm being generous at the same length that the Wolffs measure to their stated weight.  

 

So that was fun...

[troupe]

Dawson has the best extended FP to their specs.

[Michael303]

5 minutes ago, troupe said:

Dawson has the best extended FP to their specs.

It seems nice. It's long AF and actually protrudes into the chamber when the hammer is down. I can't see a scenario where there'd be a round in the chamber with a hammer down so it doesn't seem to be an issue.