Mine has a ‘bolt’ in form of a ring, to which was connected a shutter, which was moved vertically to cover the keyhole of an Invincible key lock below it. There was a long vertical safe plate (which I don’t have) bearing the index mark, and the dial rested on the upright safe plate. Mine is also wanting a spindle, which I am told was individually made, so i cannot mount it. Afaik the lock was designed to be mounted vertically.
A copy of the SAM lock sounds a surprising venture — not that I say it was not done. But it was such an expensive lock that Chatwood later decided to use something cheaper for most safes — basically, a copy of the S&G comlock. Still for the very top-of-the-range, Chatwood had the 5-spindle lock, made in batches of 5.
One uncommon/rare variant was a numerical dial. I have only seen one. At least, I was told it was from a SAM, but it might actually just have been from the Chatwood version of the basic S&G comlock.
