I was priming some 7.5x55 Swiss cases and had a couple where the primer would not fully seat. It appears that metal had flowed perfectly around the flash hole causing a ridge to form. These cases have been loaded eight times with the same load which is well below max. Has anyone experienced this problem?

BEJ,

We have found that brass does flow into the primer pockets each time you fire it.

We uniform all our brass when it is new, and run the uniformer through them again after each firing. It seems we remove a little bit of brass after each firing, which I would assume flows in from the case body.

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saeed@ emirates.net.ae

www.accuratereloading.com

BEJ ___

Am I to understand that metal has flowed back into the primer pocket preventing the full seating of the primer ? Is the "ridge" formed around the flash-hole (pocket side) and of sufficient height to contact the anvil of the primer thus preventing full seating ?

A very unusual circumstance to be sure. Please help me try to visualize what you've observed.

Good shooting.

Robert

Your image is correct.

I tried using a Lyman primer pocket tool. It didn't work. Well, it worked, but the flash hole appeared distorted after use essentially making the case worthless.

I always use a uniformer as my "cleaning" tool too. I always had the idea that the explosion of the powder pushes the web of the primer pocket downward so that on the next cutting of the uniformer a little more brass would come out. Sometimes flash holes look oblong or goofy till you look at a lite through them then I always see a perfectly round hole.

Which brand are the cases ?

I used the original Thun (Berdan) cases and, being sick of the depriming job, started with FNM Boxer cases, but did not notice the effect discribed yet.

Let me confess at this place that I chamfer the flash hole a bit from the outside as well - it's my idea that this gives the flash less resistance to enter the case. In addition, I can see whether the case has been chamfered already - and whether it is mine.

BEJ __

Okay. I can't see through your eyes, but the picture I've got (even in my usual state of total confusion) is that the center portion of the web between the primer pocket and the open cartridge case interior is protruding [centrally] into the primer cavity enough to prevent seating of the primer; much like the "hump" in a Berdan primed case.

Since that has occurred only in a few cartridge cases, could it be that the web is exceptionally thin, and "caved" into the primer pocket on-firing ? If that sounds even remotely possible, and you have found no other cause, you might want to carefully slice the offending case(s) in-half axially to exclude that theory.

Or, you might have come across a case or two that weren't work-hardened enough during the forming process. Or, ??????

Good shooting.

Robert

I've seen this in my PPC when I used a universal decapper. Dollars to donuts your decapping pin is larger than your flashhole.

Dutch.

Waitaminit - FNM cases
Dutch - Hmmm, I do use a universal decapper, but I try very hard to only go deep enough to eject the spent primer. Thanks for medulla jolt. I'm out to check it now.
Well, there is side slap when inserting the pin into the flash hole, so this may not be the answer. Also, checked the other nineteen cases and seven of them have this problem. Maybe just a box of defective cases??

Lee makes an inexpensive (about $2) little tool called a Primer Pocket Cleaner. It has the device for large primers on one end and small ones on the other. I think it's intended to be used by hand, but I put it in an electric drill and use it on every case after I've deprimed it. I highly recommend this practice. It cleans the primer pocket, and, I think, it would ream the pocket out a bit if there were metal there that shouldn't be. It does not enlarge the primer pockets, so it will not contribute to having loose primers.

Bej, hmmm. Question. When you look at the decapper, is the decapping pin centered, or does it wobble? If the pin is not hitting the flash hole staight on, it can severely damage it. This showed up in my cases as a ridge on one side of the flash hole (as you are describing), not all the way around like with the oversize decapping pin.

Conversely, are the flash holes of the buggered up cases concentric? Same result, different cause.

That was a lesson from my Redding dies..... HTH, Dutch.

The pin is tight and it takes very little pressure to pop a primer out. Yes, "ridges" are almost perfectly concentric around the flash hole. Think I'll get a Sinclair primer pocket uniformer and see if I can clean these up.