Yep that is Chuck's golf ball treatment and his tier 1 rear sight.
Front strap cut and checkering + rear cocking serrations tells me last pistol is a Baer. I think ACW did that one if I remember correctly, and the finish is Hard Hat.
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If you want to watch an old but outstanding video of a thumb safety fit, go to YouTube and enter Wilson Gunsmithing. Watch #2, which has Vic Tibbets doing a trigger job and thumb safety fitting. Pay special attention to the way he makes one file stroke at a time when he gets close. IMHO, unless you are very good with your hands, watch a lot of videos and are willing to understand the why and the how to, you should never try to fit a thumb safety. Several guys have mentioned welding the pad to add material. How many people know how to do that and have the equipment? I AM NOT saying these guys are wrong---I am just saying the thumb safety is crucially important, and if installed incorrectly can result in a disaster.