I hope this helps out a bit. I have a issue of "American Rifleman" from 1955 (I think, I need to check for sure, but think it is 1955). In this magazine there is an ad for Mershon Grip Adapters. I don't have any information to share to confirm this, other than what I "heard", but I was under the impression that Mershon was bought by Pachmayr at one time? Give me a day or so and I'll have a go at posting a photo of the ad.