I am researching this 0 size HC movement, which by the straight sided balance cock, and teeny "lock" screw in the top plate edge along the winding stem exit line tell me this is swiss. I remember Rolex did some little three finger movements like this. Anybody have a clue what this is?

It is a private label to a Jeweler in Manitowoc Wisconsin! Could well be the Canadian preferences for swiss stuff that this Jeweler got this! It's a "PURDY LITTLE THANG"!

David,
I'm not sure what it is, but I'd be very surprised if it had any Rolex connections.

I think it's a Swiss "trade" movement, but the private labelling means a little more. maybe an early Gruen deal, because he garnered a lot of sort of "independent" watch sales.

David, no cigar on this one, not even a whiff of smoke, Sorry!

I don't believe Rolex actually 'Made' any pocket watches ever, but they did buy in and 'finish' ebauches from other watch houses.
Their principle target anyway was the wristwatch market.

Even around WW2, Rolex was using ebauches made and supplied by Cortebert for their pocket watches, and on a couple of Calibres, major components between them are almost universally interchangeable right down to the dials! Even the uniquely curved index levers are identical!

If you take the dial off yours and find trademarks for 'Cortebert', Rebberg', 'Angelus', 'Unicorn', 'Marconi' or even 'ROLEX', then you Can most certainly award yourelf a cigar, as they are all names used by the Rolex brand.

Heck, if any of them Are stamped there, I'll even BUY you that Ceegaar!

If you 'Google' Wilsdorf & Davis, the founders, you'll get all the early background you want on the Rolex brand.

I would describe the movement in your watch (my own analogy BTW), as a 3rd generation generic Swiss lever ebauche with a low jewel count.
1st generation were key wind / key set (from the back), 2nd, were stem wind pin set, and 3rd / 4th generation onwards all stem wind/set.

If I've got it right from the photo of the movement, what differentiates yours as regards 3rd /4th gen ebauche is the centre wheel pinion!

The centre pinion appears to have a 'pip' which is the head of the taper stem which goes right through the centre of the pinion, and to which the cannon pinion is held by taper friction clamping both pinions together (but loose enought to rotate). The centre wheel pinion on the dial side actually stops flush with the dial plate.

The earlier 'key Set / Pin (Nail) set' ebauches, used exactly the same method with the centre pin, except where yours has the 'pip', the 'key set' type has a square head and sometimes a dust pipe on the bridge.

Later ebauches (4th Gen onwards) don't have that pin, as the centre wheel pinion is solid (except for those with centre seconds dials) and extends beyond the face of the dial plate and upon which the cannon pinion rotates and held by the usual 'snap-waist' and groove arrangement.

Quite handy differences to note if hunting around for a donor watch!

I wouldn't assume any tie up with Gruen either to be honest, although I'd be interested to know what your theory is there!

What I see there is simply a Swiss watch made for the European market bearing a name of a retailer on the dial, who may or may not have been of European descent, and who operated from a North American shop.

Given the large populus of European descent in Canada,(even though he's not actually in Canada - but close), I wouldn't think it at all unusual that the retailer would be importing movements and even entire watches from Europe to satisfy local demand.
He obviously had that demand too, because he went to the trouble of having enamel dials manufactured with his name fired into them, and I'll lay money on it that dial will fit nowt else - Swiss or otherwise!
I doubt he'd do that for a 'One-off' watch.

I quite like it David, and the 'Tumbling Numbers' on the dial is a nice touch not seen too often, thanks for posting the pic's for us.

Best regards

John