A little bit of priming powder.
Bloooop. Finding it might suck.
Done that years ago with my BIL’s smokepole. Used a sandbox to catch the jag.
No problem at all, just dug it right out.
Never heard of using a Zerk fitting to pump one out with grease, but I don’t doubt it works
I think 10 grains of priming powder would make an easier cleanup.
7mm