I have a Birmingham proofed I Hollis Ml'r that I feel sure postdates an also Birmingham proofed W Richards breech loader hammer. The I Hollis has a optional proof showing the provisional proof was not applied normally but was done at final proof with the heavier provisional load. I would have to look up the date for when this was first used but am certain the W Richards had an earlier proof. The breech loader has back action locks with a left side lever opener. The ML'r has front action locks, not sure you would call them bar action on a MLr.
