Russell,
You've been busy! I would like the best photos you have of the S.P.P. mark and the front of the grip strap. If you can avoid the glare from direct light, it will greatly improve the pictures. I have found that taking photos outside on an overcast but bright day works well. It also helps to use a background that is not too light to keep the automatic exposure from underexposing the dark gun.
You can email photos to me at
donmaus1@aol.com.
From what I can tell from the photos you have posted, it appears that there is a period between the S and P and that the grip strap has been ground. Do you agree?