Get a straw or pen or something to mark the depth
Pull the nipple and drop about 10grains down the fire channel slowly so it can get into the barrel from the 90 turn in the fire channel.
Have muzzle pointed down

Put nipple back on
Tilt muzzle up
Put some oil in it from the muzzle to give that patch some lube

Cap and fire it.
Check with the reference depth.
See if it moved.
Might even take a couple times doing this to move it.
Let the original lube from.1st time continue to soak

You might get lucky and the 1st time it goes out or gives you enough the grab onto with vice grips.



Dont ask me how I know this...
Just read the username........