Marlin model 20 22LR pump

[Melnic]

I need to get my old marlin pump out and get pictures of the internals. After fixing the firing pin I can shoot a single shot but the action locks up when cycling.

One thing I forgot to add to my post is the firing pin has a dab that sticks down into a rotating part. That tab on the replacement firing pin was not always and easily dropping into the slot. I had to remove some metal on the back side of it. The back side is NOT the side that rests on the rotating thingie which keeps you from releasing the firing pin until the bullet is in the chamber. So relieving the back side was perfectly safe.
Until I did that in order to get out of the jam, I had to make sure the hammer (or my thumb) was pushing the firing pin a little forward so the rotating thingie could fit its slot on the tab of the firing pin when it rotated up as cocked it back to load next round.
If you remove the bolt but put that rotating thingie in there if it can not freely rotate up into the slot, the tab of the firing pin needs to be filed down some

 

[easy]

What would I do? work the center punch around the perimeter in order to push steel back to support the rim?
There is a LOT of metal missing on the breech.

Sorry for the late reply, been a bit occupied.

So it's like a deep dent at the point of f/p strike(pic?)? Chamber iron or center punch would be to move the metal causing a 'snag' where the metal has been pushed into the breech/chamber mouth area. Pushes the metal back out of the way.

Have you considered using a 90*/flat crown cutter to resurface the breech end of the barrel?

Is there a missing firing pin stop?

 

[rseymorejr]

What would I do? work the center punch around the perimeter in order to push steel back to support the rim?
There is a LOT of metal missing on the breech.

If the metal is just still there just pushed out of place a chamber iron might help get it back in place

https://www.tandemkross.com/ChamberMadeChamberIroningSwage