Replaced the sear on my pre-B and encountered some inconsistent sear disengagement.
Studying the action with the slide removed a lot of sear cage movement was apparent.
Measuring with a feeler gauge between the cage and frame showed a gap of .020"+.
Euereka moment. Shim it there.
Looking for some shim material, I found a very old and tiny Kastar feeler gauge set.
Removed the .020" gauge:
Used a Dremel cutoff wheel to trim it to fit. Lucky me, width was perfect!
Enlarge the hole with a #20 drill so the shim can be retained by the safety shaft, then deburr:
Held in place with Assemblee Goo (used for automatic transmission repair)
Reinstall sear cage and safety. Worst part of it was dealing with that awful safety detent.