[Southpaw]

Most pins I have seen as Dean suggested were rounded on the ends and may jut out slightly to either side of receiver. I also thought pressure from sear spring would keep it in place. It sounds to me like they put a wrong sized sear pin in there that is to long.

Oops typed this, and then went did something else then came back and hit post. Seems you came to same conclusion. Yep I did not think it possible that pin could work the way you drew it without making it a semi-permanent feature of the gun.

BTW I am neophyte as a gunsmitty. I would almost think you could get the right pin and tap into place as it pushes the wrong one out, but then again this where things go wrong. Also don't think I would trust that pin. I would always worry it could fall out then you would be in pickle with sears flopping around.