I picked up one of the surplus 64-6`s from J&G sales,a round butt version. came in real nice cond but for some small dings. i cut the brl to 3" and cut in a slot for a partridge front blade. turned out ok. i went inside and looking at the hammer , i could see it never had a SA notch cut. it was not ground away, just never cut in. i matched up to an older K hammer and put a nice snug pin through both hammers and set it up in my small milling machine for square. I then set a carbide end mill to the depth and width of the old K hammer notch and running over to the MIM 64 hammer i cut the same SA sear notch as the old K has. after just a few swipes with a stone i reinstalled it into the 64. Bingo! ,i now have a SA notch for full cocking. although you have to start it DA and hook your thumb behind to full cock it back, it works fine. and no creep is preceptive. not bad for shooting in the dark to just copy an old hammers cut. was surprised it came out as good as it did. they must make all of them all real close over the years.
here is a pic of the 64-6 from J&G, post work. Phil