Off center primer strikes

C

cdoc42

New member
I loaded 6 sets of two different 9mm bullets with different primers:

1) Everglades Version 2 115gr HP
2) Hornady 115gr XTP

with Small Pistol Magnum, Small Pistol, and Small Rifle primers. All brass was never fired and measured at the trimmed-to size. 5 rounds in each set. All charges were measure-dropped and weighed, then trickled as needed, to the exact desired charge. All were taper crimped after bullet seating.

I did not chrono the loads. I did not perceive any differences in recoil or function with the 3 types of primers other than 2 of the 30 cartridges failed to fire. I did not think to check if the bullets differed.
When I examined them, the primer strike was at the outside edge of the primer and obviously a light strike. I chambered each by hand, and both fired upon the second try.

What might have caused the misplaced primer strike?
 
Exactly what firearm are you using? Exactly what load were you using? It matters in order to give you a meaningful answer.






.
 
What gun?
Assuming a Browning tilt-lock action, a primer indention that far off center is a case of an out of battery NON discharge. The barrel was already tipped down towards the unlocked position.
 
Its my opinion that most of the details about your handloads are a distraction.

You are looking at the wrong things.(probably). The answer is in how the gun works.
The (axis) location of the firing pin is controlled by the firing pin hole in he breech face ,which is a feature of the slide.

The axis of the cartridge case/primer is controlled by the cartridge being in the chamber of the barrel.

The barrel and the slide are two separate pieces. The alignment or misalignment at firing of those two pieces determines where the firing pin strikes the primer.

In most 9 mm semi-auto handgun designs, the breech is locked at firing. The barrel and slide are locked together with some locking lug surfaces.

They are fully locked when the firing pin hole and the barrel are coaxial.

A portion of the semi-auto cycle involves the locking lugs of the barrel and slide disengaging. This is typically accomplished by the breech of the barrel dropping down within the slide during the initial travel to the rear.

Here is the important part. For some reason,your gun is trying to fire when the slide is not 100 % fully forward and the barrel is not 100% locked into the slide.

Thats not good. Aside from your gun not firing reliably,the slide and barrel locking lugs can be damaged when firing with them not fully engaged.

A number of things can cause this.

A few might be:

A new,sluggish gun breaking in
A dirty,unlubricated gun.

Crud built up at the forward end of the chamber,where the case mouth hits the headspace surface of the chamber.

High primers.

There are more potential causes. Among them are worn or not properly fitted parts.

If you cannot see and identify what is keeping the slide from being freely and fully forward for each shot, put your fully unloaded gun in its box or a pistol rug, A chamber flag in place is a nice touch... put a few rounds of the off center firing in strike ammo in your pocket,and go visit your smiling,friendly local gunsmith.

Do not keep shooting till the problem is identified and corrected.

One thing to look at,is any bullet metal being scraped forward by the case mouth when you seat your bullets?
 
TxNimrod and Jim Watson, it's a Walther PPQ and the load was 4.9gr of HP-38 with 115gr bullets with max load listed as 5.1gr. COAL was 1.060" determined to be adequate with plunk test.

I had cleaned the gun before using it. It has approximately 600 rounds fired so far. First time I've had this issue.

HiBC, thanks for your detailed assessment. I will look into these issues. But I will have to fire it again to obtain any faulty rounds.

I have a Browning .380-1911 which, on occasion, doesn't go fully into battery and that can be identified by the back edge of the slide not being fully forward. I traced this to insufficient taper crimp.

But that has not been the case with the Walther- it has looked like it was fully forward with these two non-discharges. Is it common to have the rounds discharge as expected when inserted in the magazine as single cartridges and have them fire as expected but on the second attempt?
 
A second whack will often fire a primer.

Thats one of the alleged advantages of a SA/DA pistol. It probably is why a 1903 Springfield has a cocking knob.

In addition to the off center strike not necessarily working properly to crush the compound against the anvil, the "not quite in battery" condition may prevent firing completely,or soak up considerable hammer/striker/firing pin energy, resulting in the shallow strike.
 
Have you had this problem with the gun in the past?

If not, I'm going to suggest that the rounds you loaded are slightly out of spec and are preventing the gun from going fully into battery, resulting in the off-center light strikes.
 
JohnKSa, I am intrigued about the rounds being out of spec. Most often, with .380 Auto, 9mm, .45 APC, I won't check case length; I use a RCBS powder measure and weigh every throw for the first 10 and if they are where I want them to be, I continue throws and check every 5th to 10th throw. I seat bullets and simultaneously crimp, measuring every 5th to 10th to be sure the COAL is where I want it to be.

In this case, I was principally testing Small Pistol MAG, Small Pistol, and Small Rifle Primers, so I used new cases that happened to be at the recommended trim level. I virtually weighed each of 30 rounds thrown by the measure to assure the weight was 4.9gr. I measured each round to be sure the COAL was +/- 0.001 inch of targeted length. I crimped all after having been seated. I even went so far as to measure a new case mouth, flare and measure it, then taper crimp without a bullet to see how much crimp I got. Then I seated a dummy bullet and measured crimp again. I pulled the bullet to find the crimp was so tight it scored the bullet, making a ring, so I backed off on the crimp. Every one of 30 rounds was as equal to each other as possible.

Having a primer strike at the periphery of the primer is an entirely new experience for me. As I said above, I've fired at least 600 rounds through this Walther and have not had any problems at all up to this point.
 
I don't know about all that, but I do know what causes off-center light primer strikes in a gun with an action like yours.

It's caused by the action not fully closing.

Out of spec ammunition can prevent the action from fully closing.

Since you are using reloads and haven't had this problem in the past, it's logical to take a close look at the reloads.

Now we have an effect (off-center light primer strikes) and a cause (action not fully closing) and a possible contributing factor (reloaded ammunition).

Remove the barrel from the gun.

Drop a factory round into the chamber. I'm betting it will drop all the way in and make a "plunk" sound when it stops. Also that it will fall out easily when you turn the barrel over.

Drop one of the reloads into the chamber. I'm betting it will stop without making a "plunk" sound and that it won't seat as deeply as the factory round. There's also a good chance it will stick in the chamber and won't simply fall out when the barrel is turned over.
 
So I gather the crimp might have been the problem, and that makes sense to me. I have never had a failure to fire with the .45 APC; the episode with the 9mm Walther was a first; failure to go into battery has been rather common with my .380 Auto to the point that I don't trust it as a personal defense weapon.

I routinely do the plunk test when I establish seating depth with a new bullet, using the diagram offered on at least two occasions by Unclenick. I think my next step will be to plunk test all reloaded rounds just to see if any fail. Varying case lengths will change the crimp pressure but I never thought it would be that much of an issue if the cases were not over- or under the recommended sizes. Maybe it is a bigger deal than I thought.
 
I just ordered a Lee 9mm underside sizing die. I searched for one in .380 Auto but no luck other than going to the Lee website and paying an additional $15 shipping. I'll wait to see how the 9mm die works out.
 
The 9mm U die will work fine on 9mm for loading short slick bullets like 115 gr jhp.
It is not useful for .380, I don't see the connection.
 
I'm going with HiBC's guess of high primers. Firing on the second try is a classic example of a primer not seated deep enough. First striker hit drives the primer deeper into the pocket, thus putting the anvil into the correct position. The off center striker hit's may be because the primer is proud. Being slightly off center should not matter. Striker fired guns are more prone to displaying light primer strikes than hammer fired guns. I'd try seating the primers deeper.
 
Jim Watson said:
The 9mm U die will work fine on 9mm for loading short slick bullets like 115 gr jhp.
It is not useful for .380, I don't see the connection.
Click to expand...

If using Lee dies for .380, their Undersize die is a must. Had issues with Lee dies and no neck tension and was told by a Lee tech that there is a known issue with their standard .380 sizing die not giving sufficient neck tension. Having to buy another sizing die that costs as much as the original 4 die set kinda defeated the purpose of going with the cheaper Lee dies for me. The response about a "known issue" has since turned me off to Lee equipment.
 
cdoc42 said:
I just ordered a Lee 9mm underside sizing die. I searched for one in .380 Auto but no luck other than going to the Lee website and paying an additional $15 shipping. I'll wait to see how the 9mm die works out.
Click to expand...
Jim Watson said:
The 9mm U die will work fine on 9mm for loading short slick bullets like 115 gr jhp.
It is not useful for .380, I don't see the connection.
Click to expand...
I'm with Jim in not seeing the connection between a .380 die and off center primer strikes in 9mm.
Re the suggestion that the problem is high primers, that could explain them firing on the second go round, but it doesn't explain the off center strikes. Unless off center primer strikes are the norm with that pistol, I'm going with the slide not quite being in battery for whatever reason.
 
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