primers backing out??


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Encoreman
April 28, 2008, 01:04 AM
Hope this doesn't sound stupid. I shot a couple of primed brass, no powder or bullets and the primers backed out enough to keep cylinder from turning easily. Shot 6 rounds of loaded ammo right behind and no primer back out. Any ideas as to why this occurred? Thanks Mac. I hope this is in correct category.

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Jim March
April 28, 2008, 01:16 AM
Sounds like a wheelgun question to me.

Yeah, what's happening is, primers ALWAYS back out, but recoil slams them back in again right away.

Seriously.

What you did is, you took out the recoil :).

Virginian
April 28, 2008, 05:15 AM
Interesting theory Jim. I always figured that the charge going off kept the casing pushed back so the primer didn't back out, like on a blank, but I would like to see a high speed photo to see if the primers really do back out and then get reseated.

Jim March
April 28, 2008, 05:17 AM
T'ain't theory.

Stop and think: what else would explain what this guy is seeing?

Problem is, I can't recall where I read this :).

SDC
April 28, 2008, 07:35 AM
Ditto; you also occasionally see the same thing happen with very light "powderpuff" loads, as the recoil generated isn't enough to re-seat the primers.

Encoreman
April 28, 2008, 08:06 AM
Well that explains it, but I would have never thought this happened. Could not this reinstalling or pushing back in not flatten the primer as some do? Just thinking aloud. I wasn't exactly honest, to start with I was shooting paraffin wax bullets with only a primer. I noticed that a few primers backed out enough to almost lock-up the cylinder. I then shot a couple of primed brass without bullet to see if it would back out and they did. Thanks guys!!

Ben Shepherd
April 28, 2008, 08:21 AM
Mr. March hit it.

Virginian
April 28, 2008, 08:37 AM
I am not saying anyone is wrong, but I sure would like to see some high speed photos.

Rangegod
April 28, 2008, 09:13 AM
If you want to shoot wax or rubber bullets, drill out the flash holes to prevent primer set back.

Caution: Do not use the modified cases for normal reloads.

JAC

spwenger
April 28, 2008, 09:16 AM
I wasn't exactly honest, to start with I was shooting paraffin wax bullets with only a primer.
...Flash holes on cases used to shoot paraffin bullets can be reamed out to approximately 1/8" to prevent the primers from backing out. If you do this, he cautioned, you must mark those cases so that they do not get reloaded as live ammo.

Bill's classic book, No Second Place Winner, devotes an entire chapter to these and similar practice rounds.

rcmodel
April 28, 2008, 12:42 PM
+1

Exactly as Mr. March, Mr. Jordan, and several others have said.

When a revolver is fired, the firing pin drives the cartride fully forward into the chamber, and the primer ignites as the hammer rebounds.

Pressure inside the primer pocket raises instantly high enough to unseat the primer.

Without any chamber pressure to drive the case back, the primer remains unseated, and ties up the gun.

If you drill out the flash hole as recommended by Bill Jordan, there is not enough pressure in the primer pocket to unseat the primer.

A more modern example can be seen in the lead-free ammo now being loaded.

Some of it has nearly 1/8" flash holes to lower primer pocket pressure and prevent gun damage from the primers backing out forcefully with the more viloent "lead-free" primer compound.

There were problems with breach-face peening from the backed-out primers slamming into them so hard until the flash-holes were enlarged to prevent it.

rcmodel

Mal H
April 28, 2008, 01:11 PM
Yep - what they all said. In fact that "phenomenon" happens with almost all firearms that have any headspace at all, some more than others. The reason it is so obvious with revolvers is that as the OP found, it will cause the cylinder to lock up.

The Bushmaster
April 28, 2008, 04:05 PM
Put a bullet and powder in them cases and I bet they (the primers) don't back out anymore...

Walkalong
April 28, 2008, 04:41 PM
T'ain't theory.
Yep.
Put a bullet and powder in them cases and I bet they (the primers) don't back out anymore...
Yep again. :D

Vern Humphrey
April 28, 2008, 05:11 PM
Take an unprimed case and look in the primer pocket. You will notice the floor of the pocket has a lot more area than the flash hole. Most of the effect of the primer is directed at that floor -- if you could somehow detonate a primed case with nothing supporting the primer, it would come flying out.

The primer backs out even as the flash is going through the flash hole, before the powder ignites. Once the powder ignites, it slams the case back and re-seats the primer.

Encoreman
April 28, 2008, 10:04 PM
Thanks everyone. I appreciate the answers. I too would like to see a high speed photo of that happening.

rcmodel
April 29, 2008, 01:18 PM
Check out the damage primers do when they un-seat in a fire.

Notice especially the .223 primer damage in the third photo.
It didn't even blow the bullet out of the case. The powder burned out slowly through the flash hole like a little rocket engine.

But the primer popping out of the primer pocket almost put it through the sheet metal.

http://www.thehighroad.org/showpost.php?p=3845886&postcount=28

rcmodel

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