I do the "tilt test." every time I field strip either my M-1 or my M1-A. The ammo thing is a excellent observation. The CMP tells me it is made for the Garand with the same specs as the WWII/Korea ammunition.
Detail stripping the rear sight is another good suggestion and brings up a couple of questions. It has a lock bar rear sight. Is that what a June of 1943 Garand was born with and are the clicks the same as the later sights?
I used a laser bore sight, and yes the POI is well below the point of aim with the iron sights. I have had the gas system and both hand guards off the rifle and can't, with my untrained eye, find a problem.
I have a IHC service grade on order... maybe I can fiqure out something by switching parts around.
BTW I "carried," a M-1 Garand in 2 years of ROTC in college... Then I "carried," a M-1 during 20 weeks U.S. Navy Officer Candidate School that was operated by USMC Drill Instructors. I had my Garand tossed over 3 ranks and into a sand pile where it stuck like a javelin. I was then given 5 minutes to field strip and clean the sand out of the rifle... blindfolded.
Just so you will know, in all that time and all those miles of drilling, I never fired a Garand and never saw one with a firing pin.