Jack,
I will say that I have heard this,and as a long time reloader,I have done it.
Please note that I did this with a reloading press,not a rod and hammer.
While I never had one explode while removing that primer,there is a very good
chance that it could happen.A very good chance.
I say explode because priming compound is a high explosive, it just happens
to be in a very small quantity in a primer.
IF you choose to proceed,please wear hearing protection,a faceshield,and heavy gloves.
I would recommend you DO NOT try this.
There is a piece of foil over top of the priming compound,underneath the anvil as it's called,coming from the inside of the casing,and on the chance the foil sealed things off
really good,and oil didn't reach..POP!

My depriming was done on a single stage press with a loose fitting decapper die,and you
can control the pressure,like a squeeze.
If you try this manually without a press,you will have to tap or hit sharply,
please don't do this.Really.it's much like a firing pin strike (opposite side,yes,but..)
I have fired off empty primed cases in guns to kill the primers and you would be
VERY surprised at the noise and fire and power just from that primer.
Bottom line,be safe,soak in oil, and dispose of the live primers.:biggrin:
Casings are cheap,your body parts are not.
If you need some .308 or .30-06 cases,no primers,please pm me.I have scads.