Primer Seating Gone Wrong

[powerspc]

HI, I just started reloading .357 Magnum. I am using Hornady Brass, VIHT-N110 Powder and WSPM Primers. Today I had 6 misfires out of 24 rounds. Knowing that the odds of having 6 bad primers in a single range session is a statistical impossibility (modern primers are reliable 99.9997 percent of the time meaning you might experience a bad primer 1 in every 300,000 rounds) I can clearly put the blame on my reloading technique.

As a place to start, is it more likely that I am seating the primers too deep (crushing them) or not deep enough (creating a cushion)? Or are those possibilities equal in their ability to cause a misfire? I am using an RCBS Automatic Bench Primer Seater. The other 18 rounds fired perfectly and all rounds had identical primer strikes out of an S&W 686 revolver.

 

[KZP]

Just to make sure, do those 6 misfire rounds have powder in them? I've had a few in the past where I thought it was a dud primer but I somehow didn't load powder.

 

[Slo cat]

High primers can cushion the strike and result in a dud. I have never heard of a too deep primer seating being a problem. A light strike can also be a pistol problem. Have you lightened the springs in your revolver? A cartridge with no powder almost always results in the primer gasses driving the bullet out into the barrel, or nearly so.

 

[Huskydriver]

I think all of my primer misfires, and failures to fire have all been using Winchester primers when reading for my 44 mag.

 

[powerspc]

They had powder in them but always a good place to start; the only thing I've seen on seating too deep is that you can over-compress the anvil causing the primer to "tilt". I'm thinking high primer, i.e., I may be being too cautious in seating them. The gun is new and the 686 should in theory be one of the most reliable handguns in existence. That said, I have other revolvers I can use so maybe I'll try seating with a little more authority and try those rounds in another gun. If all goes well I can switch back to the 686 and see if the problem went away or if it might possibly be a "gun issue". Not ruling that out. Thanks!

 

[ingraham]

I've just start reloading and have primed my first 5 cases. I'm using a RCBS hand primer. It doesn't look like it is seating the primers deep enough. I'm using once fired Winchester cases that have been full length resized and primer pockets have been cleaned. CCI BR primers. I can see the tiny dimple the primer rod left in the primer and it feels like it has stopped moving. I used my calipers to measure some factory Winchester and they seem to be seated 0.005 like the manual says and some hornaday which are actually 0.008. When I measure mine they are only 0.001. The case sits flat on the bench but you can feel the difference with your finger. Any suggestions??

 

[Holliday]

I use a 21st Century Priming tool. Once you set the clicks, write them down.... same depth every time whether the pocket is tight or getting loose. Some folks have concerns about loading each primer into the tool manually but I don't find this to be an issue or slows me down much at all. http://www.xxicsi.com/stainless-steel-priming-tool.html

 

[pmclaine]

Primers are nothing to fool with.

I blew a stack of ten or so in a progressive and have the underwear to prove it. It belled a shielded steel primer tube and melted/blasted the aluminum tube inside of it. The push rod made a nice dent in my ceiling (Dillon). Operator error on that one if it doesnt feel right - stop.

A primer even without powder will push a round into the barrel.

.357 mag I assume you are shooting a revolver.

Thats a lot of mass striking the primer with a typical revolver hammer.

Even seated high surprised they wouldnt fire with a shitty lock time to push them to crush the anvil.

If you sit your rounds on the case head and they wobble you are not seating deep enough.

You should be able to catch a fingernail on the primer pocket when seated properly.

Winchester did have some primer issues a few years ago but it was a "piercing" problem scoring up rifle bolts.

Interested to hear your solution.

 

[MarinePMI]

I think I've only ever had 3 or 4 dud primers in my years of reloading (30+ now). this sounds like either they were not seated fully, or some how contaminated. Even then, it takes a lot of contamination to make a primer not go bang.

As pmclaine says though, primers are not anything to screw around with. I had one go off while priming cases once. I'd wager a piece of tumbling media (corn cob) was in the primer pocket and I wasn't paying attention (or wearing eyepro). Fortunately, I was in the habit of keeping the case tilted slightly, so all I got was a nice raw burn on my forehead/eyebrow when trying to force the primer to seat. Lesson learned; always wear eyepro when priming, and also never try to force a primer to seat when it doesn't want to go. Slow, but firm, steady pressure.

 

[Juggerxxx]

Can you post a picture of what those primers look like that you had problems with. If so; post a few pictures at various angles. Seeing that could paint the answer.

 

[ingraham]

You could investigate a few things:

1. examine the end of the ram on your handprimer, to make sure it is smooth and cut perpendicularly.
2. make sure you're using the right case holder for your caliber.
3. determine whether the handprimer's ram stroke is long enough to fully push the primer into the case. Using a small metal straightedge laid onto the bottom of the case holder, can you feel the ram touching when it is fully raised? Does it want to push the straightedge upward? If yes, that is good.
4. If the anser is no, measure & compare that case holder to others of the same brand to see if it might be too tall. A too tall holder will keep the case head out of reach of the handprimer ram. (not a likely problem)

5. gather a sample of say 20 cases and number each case with a sharpie.
6. make sure the primer pockets are clean, free of burrs or combustion debris.
7. for each case, mic the depth of the empty primer pocket, and note this down.
8. mic the height of 20 primers. Note this down. Pockets should be deeper than primer height.


9. firmly seat the 20 primers into the 20 cases. Use the tail end of your caliper to measure the amount by which the primer is seated below the case head. You're looking for 4 to 6 thou, give or take. Compare this difference to your notes. What's important is that the case not wobble, and that your thumb can feel that the primer is below the case head.

10. primers are quite resistant to slow crushing, but will go off if given a blow. Wear eye & ear protection. After awhile, your thumb will get a feel for a fully seated primer and you'll be gtg.

 

[ShtrRdy]

Does this revolver have reduced hammer spring or some trigger/hammer work done to it?

 

[buffalowinter]

Occam's Razor would suggest that the primers are not fully seated.

 

[powerspc]

Problem solved I think; I loaded 25 rounds today paying careful attention to making sure the primers were seated all the way to the bottom of the primer pocket. I then measured the depth of the primers and found that it varied between .002-.007. I separated them into groups of .002, .003, .004, .005, .006 and .007. All rounds fired perfectly regardless of seating depth.

I’m thinking now I may have been going too fast the other day and “limp wristing” the primers creating an air pocket between the primer and the primer pocket which provided just enough cushion to cause them not to ignite. In the pictures below are one of the misfires (left) and a round that fired (right). I tried firing the misfires a few times so it looks pretty clear it’s wasn’t a light primer strike. For now I’m satisfied with that explanation and appreciate all the help!

 

[MarinePMI]

Sounds like you're GTG now.

As an aside, like Mike @ MHS stated in the EDS podcast, I seat a primer, then rotate 180 degrees and seat again to ensure the primer is fully seated around the complete circumference. Only adds a second or so, when priming with a hand primer. Does it make a difference? I don't know. But it's cheap insurance to ensure that the primer is fully and squarely seated.

 

[powerspc]

Sounds like you're GTG now.

As an aside, like Mike @ MHS stated in the EDS podcast, I seat a primer, then rotate 180 degrees and seat again to ensure the primer is fully seated around the complete circumference. Only adds a second or so, when priming with a hand primer. Does it make a difference? I don't know. But it's cheap insurance to ensure that the primer is fully and squarely seated.

Sounds like belt and suspenders, never a bad idea, thanks!

 

[spife7980]

Sounds like belt and suspenders, never a bad idea, thanks!