Primer failure.....What to do?

[Robinhood]

Only one way to tell. Get a case headspace gauge or borrow/make one. Or use tape on the sized brass to tell how long the headspace is on the cases.

[bigedp51]

Only one way to tell. Get a case headspace gauge or borrow/make one. Or use tape on the sized brass to tell how long the headspace is on the cases.

The best way in my opinion would be to use a Hornady cartridge case headspace gauge.

Then measure fired cases and again after resizing to check shoulder bump and head clearance.

I did this on three different AR15 rifles and settled on .003 shoulder bump.

I also collected mil-surp rifles and many have longer headspace settings and this is where firing pin protrusion comes into play.

I have .303 British Enfield rifles, and at maximum military headspace you can have .016 head clearance if the rim thickness is .058.

My first guess is the primers were not bottomed out in the primer pocket and the firing pin hit was cushioned.

My second guess would be defective primers for whatever reason.

That being said I have a Lee .223 die that will push the case shoulder back .009 shorter than the chamber. And this is with the die making hard contact with the shell holder with press cam over.

The Lee die is the worst die I have for excessive shoulder bump if the dies directions are followed, meaning with the die contacting the shell holder.

Bottom line, the OP needs the Hornady gauge to measure fired cases and resized cases. Drop in case gauges like Wilson are hard to just eyeball when you get older and a digital vernier caliper is very easy to see.