I have an old style ABC 1.0018kg silver bar that I dragged out to sell but noticed a counter stamp of SR Mitchell on it. Now, I've done a little research on it and found that ABC opened in 1972, and SR Mitchell refiners & co opened in 1920 although I don't know when they closed. Will post a pic tomorrow because my new phone now doesn't save in jpeg apparently so I have to do it the long way and not sure where my camera is. Anyway, to cut the rambling short- I think that its a SR Mitchell bar with ABC counter stamp rather than ABC counter stamp Sr mitchell. Unsure of the age however. Would be great to hear your thoughts.
I would love to see a photo but I suspect you are correct. The Mitchell bars are possibly quite old but they did trade until the '80s I believe.
I just acquired one of these bars myself I believe mine is from the late 70's or early 80's. This is my first post on this site, and I'm using a mobile, so please forgive me if my photo doesn't work. Source: http://s8.postimg.org/6q1auicph/image.jpg
I believe both these bars are circa '80s. Good bars for Aussie kg collectors along with the long Perth mint kg bar with "THE PERTH MINT" stamped on it. The first bar has the SCCC flower counter stamp on the front. Seems like SCCC stamped bars indiscriminately on the bar, front/back/rotated. Hmmm.... I have an idea! You'll see it later in the day!