Primer setback after firing (with no powder load or bullet)

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watermonger

watermonger

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I just reamed a LPP pocket on a single piece of 10mm brass down to an LRP with a pocket reamer, I wanted to see if my Glocks striker would be potent enough to set off these CCI magnum LRP's and after loading the empty casing with just the primer and dropping it into the chamber it fired but I noticed I had a hard time racking the slide back and once the casing was out I noticed the primer had gone from flush to sticking out after firing. Is this something that only happened because the round was empty and lacking a projectile and powder load, or would this happen even with a fully loaded cartridge and if so, what could be causing this?

Pictures of the primed casing.
kCLEE2X.jpg nmfZ59R.jpg
 
When the primer goes off the first thing to happen is the pressure pushes the primer out of the primer pocket. When the powder ignites and pressure builds, the case is pushed back against the breech face/slide and reseats the primer. With no powder/pressure to reseat the primer in the case it can cause the gun to kind of lock up.
 
watermonger said:
Is this something that only happened because the round was empty and lacking a projectile and powder load. . .
Click to expand...
The primer exited the case as far as the headspace allowed.
It happens every time, but in a normal firing cycle the pressure of burning propellant seats the brass back over the primer.

You've just discovered why blank brass has oversized flash holes; make the hole big enough and the primer won't back out.
 
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I made up some 38 special rounds with a wax bullet a while back. I took 38 & 357 brass with damaged mouths & beginner cracks and cut it shorter so I could eliminate the bad spots then drilled out the flash hole to I believe 1/8"
Loaded just a primer and pressed in a wax plug. On the first few I had not drilled out the flash hole o the primers backed out, but I fixed that
 
Not exactly scientific. But I once took 5 primed 380 Auto cases, one by one I fired them off. Three of them with the muzzle pressed into a pillow. Two of them in the open air. The primers of the three into the pillow, the primers remained seated. The two into the open air, the primers backed out considerably.
 
kcofohio said:
The primers of the three into the pillow, the primers remained seated. The two into the open air, the primers backed out considerably.
Click to expand...
As already mentioned above, this isn't what is happening.

When the primers are fired, they back out of the primer pocket due to the pressure created. (opposing equal force in opposite directions) They stop against the breech face. They are then reseated in the primer pocket as the case is forced backwards during recoil. If there is not enough pressure to cause the case to move to the rear, the primers remain protruding out of the primer pocket.

Unless primers are held in the primer pockets by having a crimp applied, they all back out when fired. If they get reseated has to due with the pressure created to push the case to the rear
 
I've had something similar happen with light loads in one of my rifles.

Thanks for asking the question though. It's good to share experience when "experimenting". I've tried different cases loaded with only a primer but didn't think about the proud primer when I was finished.
 
Mine did the same when I tested SPM's on my model 23's striker. I attributed it to being empty as mentioned. Didn't have any issues with it after I shot loaded rounds,
 
edwardware said:
The primer exited the case as far as the headspace allowed.
It happens every time, but in a normal firing cycle the pressure of burning propellant seats the brass back over the primer.

You've just discovered why blank brass has oversized flash holes; make the hole big enough and the primer won't back out.
Click to expand...
Exactly!

edwardware said:
Au contraire, that's exactly science!

You wondered a wonder, and did an experiment; a lab coat and a dozen post-doc research assistants wouldn't make it more scientific.
Click to expand...
The only improvement would be a larger sample size. To satisfy the statisticians. :)
 
I had the same problem when I made up some "Carpenter bee" loads for the .44 mag I had no problem out of my TC Super 14, but they locked up my Ruger Redhawk with the same load.
Either open up the flash hole or convert them to 209 shot gun primers
 
Yep, 15 posts saying the same thing (my turn); normal loaded round fires, primer backs out, pressure moves case back reseating primer against bolt, breech face, or recoil shield. No load with primer only; primer fires, pressure forces primer back, not enough pressure to move case to reseat primer. Not a lot to do with case sealing chamber as the case has to slide back to reseat primer...
 
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