That is why the 45 Auto Rim was developed. Try shooting one of those in a 1911.
The headspace is measured from where the rim on a rimmed cartridge sits on the cylinder to the breechface or the vertical face directly behind the cylinder.
What you are talking about is the cylinder throats and here is an explanation on that. The cylinder throat is to guide the bullet from the cartridge case into the throat of the barrel.
I am sure that your 1917, 625 and 610 can reliably fire the rounds but extraction would have to be a pain as the extractor has no rims to push against to extract the cartridges. Can you take a video of your shooting one of them and how the extraction works. I would really be interested in seeing that.
My offer still stands and I would even pay the shipping. ✌