It's a pity that all rimfire semiautos don't have a cross pin to prevent the firing pin from hitting the barrel in a dry fire, like Rugers.
Even if the back of the barrel is machined like you suggest, it's bound to happen again.
Just keep your handy tool handy.
On one of mine, that suffered from this problem, I filed a notch just deep enough so the firing pin can't peen the back of the barrel enough, any more, to interfere with a round chambering.
And narrow enough so the rim of the case is still well supported, so the firing pin sets it off.
So far, so good with it.
Walt Kelly, alias Pogo, sez:
“Don't take life so serious, son, it ain't nohow permanent.”