I have a bunch of these cases mixed in,  the primers seem to have a lip to them, sorta like a  rimfire case, except its a rimmed primer.  The rim is less than 1/32 of an inch.  after being deprimed, the case looks like an overly swagged case.

I swagged one and primed it to be sure it would work out, seems to work just fine,  primer has a nice snug fit to the right depth.  These have got to me semi-common, but I couldn't find any other posts about them.  I have LC and Hornady cases like this.

My best guess is that the cases were reemed before, loaded, and the primers filled the space in the primer pocket when they were fired.

Yes, 223.  I think one of the batches I purchased in ee was a bunch of range pickups because I also got some live "blank" ammunition.
The cases shown are of this type, the one on the right I re-primed.

it looks like the brass was over swagged, on a high powered round it may blow the primer apart

Looks like military primers are in order for reloading these then.  I may try to manually separate them out if possible, but I have a 5 gallon bucket full and about 1-3% have this issue.

Quoted: Is the left hand case one with the blown out primers?

yes, all 3 cases had the blown out primers. the one on the left is yet to be de-primed. It is also not the best example, but I deprimed the best examples I had. At first I thought I had some 223 cases which were modified to fit large rifle primers.

Quoted: These fat primers were not protruding from the case before you decapped?

The fat primers were not protruding beyond the base.

Quoted: This may seem like a really dumb question - did you use a small rifle primer in the case you re-primed? I was expecting to see primers with a very flat flange, similar to a shotgun primer.  Right now, I don't know what to think about these without more information.

yes, its a small rifle primer, and it fits just like a normal 223 case when inserting the primer, also I could not get the primer to move once it was seated by tapping the base of the case against a vice, even when being overly harsh.

After recounting the decapped primers it looks like around 5-10% of my 5 gallon bucket might have this issue.  DOH...

Well I didn't do the re-loading so......I'm speculating.

That mushroom head look on the spent primers and the pic of your newly seated primer in the suspect brass, tells the story.  It appears that the chamfer at the opening of the primer pocket was "over done." A swage or a reamer, when not properly sized or adjusted, could be at fault.

I use a reamer but, I don't have "those" sort of problems.  I suspect that the guy who did your cases, IF HE USED A REAMER, may have used the wrong tool.  Something like, THIS STYLE OF TOOL..........

www.midwayusa.com/eproductpage.exe/showproduct?saleitemid=364181&t=11082005

When he should have been using..........something like these tools, Large Primer Pocket Size #7777785

www.midwayusa.com/eproductpage.exe/showproduct?saleitemid=682934

Small Primer Pocket Size #7777784

www.midwayusa.com/eproductpage.exe/showproduct?saleitemid=643126

Then, IF the re-loader had used a swage........then, it could be that the adjustment was wrong.  And/or the swage rod may have been modified to "over expand" the area.  And/or the swage rod may need modification.

Aloha, Mark

PS.........BTW, if those primer pockets are over sized and/or the chamfer over done, the primers themselves may not have all the support that it's use to.  Thus, when the rifle goes off the primers are also backing out and being slammed against the bolt face.  It appeas as a flattened primer, expanding to the space available.  Sometimes people may think it's, indicating an "over pressure" condition. Though, it could also have to do with the amount of (friction) support, that the primer pocket is not giving the primer.  Thus, just watching for the classic flattened primer, "overpressure sign," isn't always exact enough.

I think previous reloader over swaged mil-crimps on the LC Brass. You can see too much crown/bevel/lip on primer pocket. Primer just balloned possibly due hotter load. What you suspect is probably correct. If you dont want them ,I'll take some donations  =)

I've cleaned up nearly all my crimped cases with a chamfering tool and my spent primers look quite similar, though I've never had a ruptured primer.

I'm not one to load things lightly, either.

Over-reamed.  You cannot over-swage.  Adjust your swage for crimped brass.  Try some non-crimped.

Looking at the primers alone I'd say it was a head space issue. But looking at the primed case on the right I don't know what to think.