Backing out primers mystery

[TAROMAN]

Been handloading over 50 years and have never encountered anything like this.
While practicing for next Saturday's match, I experienced several misfires. Odd. Opening the cylinder was difficult due to the struck primer being backed out.
The details:
38 Special, 160 Bayou round nose coated.
3.5 grains Bullseye, chronographed at 755 FPS.
Federal SP match primers.
SD: 8.15, good load, used it for years.
Brass: R-P 38 Spl +P
Gun 67-3.
Brass sorted from a recently purchased a large lot of fired brass. Being OCD, I sort everything by headstamp.
First time I loaded these.
Primed using an RCBS hand tool, ensuring each is fully seated.
After the first happening, I double checked each cylinder load.
Only thing I can imagine was some loose primer pockets.
Would appreciate any and all thoughts on this.
I will discard all these cases.

 

[glenwolde]

To my knowledge primers backing out occurs because of low pressure. For example if you've ever shot wax bullets with just a primer you know the primers will back out if you don't drill out the flash holes. If you fire an empty case with a live primer it will back out.

But I would think you would have noticed other signs of low pressure. I have had some problems with Remington brass and bullet pull on 125gr bullets that don't have a whole lot of bullet in the case. Remington brass is very thin. I resolved the issue with the 125gr by using a Lee U die, with the U being for Undersized.

Doesn't really sound like that's your issue though. It's a conundrum.

 

[Sevens]

To either further what is said directly above or to clarify it…

Primers tend to back out of EVERY cartridge, but also happening in short order is that the cartridge case is backing up too, which either prevents the primer from getting far… or quickly driving the primer right back in.

I typically load 158’s with the same charge of Bullseye, that’s a classic load that’s been used in a billion rounds of ammo, so your powder and charge weight is nothing out of order.

I’d say this is an odd and interesting occurrence.

 

[glenwolde]

To either further what is said directly above or to clarify it…

Primers tend to back out of EVERY cartridge, but also happening in short order is that the cartridge case is backing up too, which either prevents the primer from getting far… or quickly driving the primer right back in.

I typically load 158’s with the same charge of Bullseye, that’s a classic load that’s been used in a billion rounds of ammo, so your powder and charge weight is nothing out of order.

I’d say this is an odd and interesting occurrence.

Yes, that's a better way to put it. So from the reverse point of view the answer could be that these cases are sticking in the chambers and not "reseating" the primers. But I don't see why that would happen. Makes no sense. Like you said, it's a common load. Especially odd that it's just one brand of case.

OP: did you inspect the primer holes? Maybe something is going on there? All I can think of.

 

[Bruce51]

My guess is insufficient pressure due to light to no crimp.

The Bayou 160 grain bullet appears to have no cannelure.

That's all I have!

Bruce

 

[Dennis2149]

Previously fired brass. Could have been reloaded hot many many times and enlarged the pockets. Also, is the cylinder end shake within specs?

 

[toad67]

Sounds like someone loaded up a bunch of +P loads and stretched the primer pockets, then decided to unload their junk on someone else...

 

[TAROMAN]

Thanks to everyone.
End shake was one of the first things I thought of. Negligible.
Crimp is something I hadn't considered.
I use a Lyman M case expanding die and Lee crimp die.
Don't crimp heavily. Possible thinner brass is part of the issue.
Beginning to believe a combination of factors may be involved.
Sort of like the Swiss cheese model explaining accidents.
I'm going to make up a dummy to measure crimp.

 

[Sevens]

Sounds like someone loaded up a bunch of +P loads and stretched the primer pockets, then decided to unload their junk on someone else...

Seriously doubt this. Occum’s razor. If a handloader did something that he later fully realized was reckless and undesirable, tiny chance he would try and get money out of a few pieces of suspect brass and potentially create a safety issue for someone else.

 

[TAROMAN]

Brass came from a commercial vendor specializing in LE brass.
Purchased a batch of 500. Mix of R-P, WW, Speer, and Federal.
Nothing imported or off-brand.
Just measured a loaded case mouth. Taper crimp .370" as close as my cheap caliper can go.
Next batch I'll adjust it a tidge tighter.

 

[Alk8944]

From Sevens post #3 above. "Primers tend to back out of EVERY cartridge, but also happening in short order is that the cartridge case is backing up too, which either prevents the primer from getting far… or quickly driving the primer right back in."

The load is not developing enough pressure to overcome friction between the case and chamber and cause the case to back-up and re-seat the primer. There are numerous things that can cause this. weak mainspring, crimp, load is actually less than 3.5 gr., etc. Start by checking the mainspring, crimp, and verify load. If the load is correct you can bump it up .1 to .2 grains and this will fix the problem.

 

[cmj8591]

I'm going to bet that you replaced or modified your main spring in your 67 or your strain screw is short or backed out. A weak mainspring will cause a primer to back out. That load shouldn't be a problem with over/under pressure. Replace the main spring and tighten the strain screw and I bet it goes away.

 

[TAROMAN]

Correct, I tuned it for fast DA shooting in steel challenge.
probably a perfect storm of circumstances.

 

[Mike SC Hunter]

To either further what is said directly above or to clarify it…

Primers tend to back out of EVERY cartridge, but also happening in short order is that the cartridge case is backing up too, which either prevents the primer from getting far… or quickly driving the primer right back in.

I typically load 158’s with the same charge of Bullseye, that’s a classic load that’s been used in a billion rounds of ammo, so your powder and charge weight is nothing out of order.

I’d say this is an odd and interesting occurrence.

YOU ABSOLUTELY POSITIVELY NAILED THE PROBLEM.

 

[TAROMAN]

What's weird is these primers are struck, but rounds did not fire.
Bullets not dislodged as in a no powder case.

 

[glenwolde]

Winchester primers?

 

[glenwolde]

Winchester primers?

Never mind you said Federal

 

[Beecherkid]

Another thing to check is the hammer nose bushing.

If it is inset in the frame, that will allow the primer to stay backed out of the case when the cartridge is fired. Check it with a straight edge across the frame to be sure it is flush.

I experienced this problem once. The average "street corner" gunsmith cannot repair this as the new firing pin bushing has to be installed with a special tool for staking. Smith & Wesson will repair this for a reasonable cost.

I hope this information helps.

 

[glenwolde]

Not the same issue, but I recently had a box with 30%-40% misfires. I pulled them all to see what was up. They had the correct charge of powder and it was fine.

The primers looked weird. The primers did not look new/unfired. They had a less-than-normal burnt look and a weird slightly greenish tint. I guess just some bad primers. Did you pull all yours? Did the primers fire even a little?

I suppose they might have backed out if I had shot them in a different gun.

 

[biku324]

It's been a long, long time since LE used 38 special in quantity, and often agencies used remanufactered target ammo for training. Used brass is a ****shoot.