Everything is now all repaired and range ready. This particular firearm (4506-1) functions / cycles great with my 8 round Model 645 S&W mags, and with an 8 round .45 caliber S&W mag marked "This Magazine....with Yellow follower". I had mags for my S&W 4566 but didn't realize that the mags I had for that will not function in my 4506-1. I guess I didn't realize there were mags through the life cycle of 2nd & 3rd Gen S&W 4500 series guns that are different enough that they will not work if exchanged between the 645, 4506, 4506-1, 4566.