Any ideas?

[338 dude]

Maybe when you seated primer over did it a bit. or it went in a touch sideways and got a bit deformed?

I don't think so I use a Frankford arsenal hand primer it has a depth setting

 

[ButterBean]

Was it just the one ?

 

[338 dude]

Was it just the one ?

Yes sir

 

[338 dude]

One way or another I think it can only boil down to a defective primer. We just take them as they are and load them everything else we adjust, but with the pressure involved I don't understand it being concave.I've heard of low pressure loads collapsing the brass neck or shoulder but not the primer

 

[ScottB338]

Looks like a dry fire strike on the empty case. Might try to duplicate it by dry firing a different case and compare.

 

[fmuguira]

I ve seen somewhat concave primers when starting load development and beginning with minimum starting loads. As pressure ( powder charge) goes up the primers start looking 'more normal'.

It seems to be more prevalent on some guns than others; don't know if it's because of headspace differences, firing spring pressure or what. As Bean mentioned/asked, since it was only one round I d keep on eye on them and continue on. Possibly a slightly out of spec primer cup ( thickness) or something ….?

Good luck.

 

[johngibbs222]

I use S&B primers exclusively for 308 and 223 and have noticed this regularly on the 308. I initially thought along similar lines to post #25. It's a hard one to call as it only happens with speer 165 grn spbt cup and core bullets, doesn't happen with 130 grn barnes tsx or 147 or 150 fmj boattails.
The load I have with the speer bullets is 47.4 grns N150 giving around 2700 fps muzzle velocity, 3 shot groups of about 3/4" and the only thing I can think of is that there's much less pressure when firing.
With the same bullet and primer with 47.9 grns of CFE 223 gives around 2800 fps at the muzzle but 1" 3 shot groups it doesn't happen.
FWIW I neck size only and use LEE's factory crimp die on every load.
In the image below, the three federal cases had 47.5 grns of N150 and 147 grn bt fmj bullets, the 4 GGG 7.62 cases with black felt marker ink had 47.9 grns of N150 and 150 grn BT fmjs the remainder of the fired GGG 7.62 cases had the speer 165 grn bullet in them loaded as stated above and the dishing is visible on some of them.
Hope this helps. The GGG cases are nato 7.62 once fired (in my gun) match cases. So that may have something to do with it.
The federal cases have upwards of 15 reloads through them and have been retired.
I also added a pic showing the target I shot as I built up the hunting loads for the speer bullets.

Gun is a ruger #1, chrono is magnetospeed sport.

 

[338 dude]

Looks like a dry fire strike on the empty case. Might try to duplicate it by dry firing a different case and compare.

Winner winner chicken dinner!!!! I said I noticed nothing out of the ordinary when hunting that day your statement just jogged my memory. I thought after one shot I short stroked the bolt and did not load a round well, apparently I did not eject the previous round and could have hit the primer on an empty case!

 

[rsbhunter]

Low pressure doesn't make sense to me (doesn't mean it's not). It takes 50,000 psi plus to flatten a primer.... It would have to be a weird situation to have enough gas at back of case to dish primer cup..???

 

[nealm66]

Winner winner chicken dinner!!!! I said I noticed nothing out of the ordinary when hunting that day your statement just jogged my memory. I thought after one shot I short stroked the bolt and did not load a round well, apparently I did not eject the previous round and could have hit the primer on an empty case!

So you're able to replicate by firing on a spent cartridge?

 

[Mike Matteson]

I am thinking powder charge was to much in that load only. If is hadn't occurred before. I note possible eject mark, with a creator. I can see you have probable reloading for a great many years. Possible when putting in the powder charge into the case with a funnel ( Not sure what you using to place powder into case) before some powder got hung up from prior case being powdered. Just a thought.

 

[338 dude]

Here are before and after pics of just duplicated the situation and seeing as how I did short stroke the bolt

 

[rsbhunter]

I believe that might be the case, but as stated, I have had that exact look on 45 acp primers that did go off, one firing pin strike....? just in case there are multiple causes....Thanks, rsbhunter

 

[338 dude]

I'm sure there are several ways it can happen I know about low pressure loads but in this case with me thinking or rather knowing I short stroked the bolt I believe this case is solved. Thanks to everyone for their help and suggestions!