With all due respect Garbler any gunsmith who can not fit a S&W hand has no business calling himself a gunsmith. The tip does not have to be filed and shaped it come that way and the tip only carries the cylinder through the first 30 degrees of it's 60 degree rotation(assuming a six shot). The balance is accomplished by the side of the hand is more of a pushing than lifting. Here hand thickness is paramount. You generally don't have to do any work to the window in the frame unless it is a really old worn gun and then at most you just square it up. The ratchet teeth will all be the same height. If they are not then someone has messed with it and it is time for a new ratchet. Here it is a good idea to send it in as S&W can cut the teeth on the ratchet while it is installed in your gun and most Smiths don 't have the broach tool to do this properly. A S&W repair guy can cut all six teeth in less than a minute. Really all you need to do is measure your hand window and order the correct thickness hand if it needs to be reduced a bit a flat bench stone makes short work of it.
Do general gunsmiths send out work they are not comfortable with or not really set up to do ? Of course they do and whether people want to acknowledge that a gunsmith cannot cover all the bases and needs to farm out some work to keep a customer happy should not be earth shattering news. As long as the shop is doing what is best for his customer. Almost every rifle maker does the same with outsourced barrels, triggers, stocks or finish work. They put it together, chamber it and make it work for the customer. Not every gunsmith specializes enough in S&W work that he wants to tackle fitting up an oversized hand or run into a series of problems with the frame or ratchets so he sends it out. So what ? If you want a specialist that is fine and they are out there but often a gun shop is a local business that takes what ever comes through the door in order to keep the door open and I respect a man who knows his limits.
As for your other points I agree on many and differ on others. With oversized hands from .096 to a full competition hand at .102” you will have to file and open the window to varying degrees and this must be done dead nut on or the hand will push off and not engage the ratchet lugs properly. A sloppy hand window cannot support the hand during it’s travel to rotate the cylinder and the dirtier the gun gets the more rotational resistance you get which will cause skips and timing issues. Furthermore S&W hands are hardened and as such if the tip is not shaped a bit they will score the ratchets which are much softer. With guns that have been shot a lot it is pretty obvious. Then there is the matter of hand tip protrusion beyond the recoil shield and what is tolerable and what is not. On K & L frames the hand tip cannot protrude at all and therefore some stoning may be required to the hand belly and at the same time this must be done properly so the hand remains vertical or parallel to the cylinder. Can you buy a new hand, drop it in, and expect it to function properly ? Yes and No but it all depends on the condition of the gun.
I did not know Smith & Wesson would re-machine ratchets so this is something I am just learning. Years ago they would not and would only sell you a new cylinder. This I think is good news. As for all ratchets being the same size or height ( riding or engagement surface ) well perhaps the newer guns built on CNC machines are indeed that uniform but trust me the older guns were not. Wishful thinking there and to fit a oversized hand you really need to find the lowest ratchet lug of the six and fit to that one or you will have problems.
I used to maintain and repair a lot of range rental guns and worn hand windows, hands and ratchets was very common and a pretty steady business for a while. I watched a S&W custom shop mechanic one time show me a technique they used to bend/peen the hand tips to the low ratchet with a plastic hammer hard on the cylinder. It worked but nothing I could get the hang of. Bending or peening the tip of the hand is in essence bending it to make it act like a thicker hand where the offset makes up for the sloppy window — a temporary fix but it does work if done delicately. Ron Power showed me the same thing about twenty-five years ago at a gunsmith school. In fact it was Ron who showed us how to fit up oversized hands and how to find and stone a hand to the lowest ratchet lug. . So this is not just my opinion but that of probably the premier Smith & Wesson mechanic in the country.
I am thinking you are a gunsmith and if so I wonder if you have fitted up many hands on the older revolvers ? Or maybe most of your work is on newer guns ( post 1990 ) where parts and tolerances are much more uniform than I am used to. When I was in the business most of the repair market was older pre-CNC guns that were assembled from the parts bins one at a time on the benches. Back then the model 41’s and 52’s and a few others were all assembled in the Custom Shop where they had the ability to fit up a gun the old way one part at a time and the parts were sorted. As I recall the Custom Shop and all of that old talent went away when Steve Melvin and the British took over S&W . They installed CNC machinery and considered the old fashioned hand fitting of parts a throw back and an inefficient waste of time and money. Some of the guns coming off the line in 1990 were absolutely abhorrent and I recall J.D. Jones and myself going at it with S&W and the ‘ new and improved ‘ mind set of this company with and their newly released 625’s. They thought they could actually mill it and send it out and nobody would be the wiser. There was no real QC or gun builders on the job.
In fact I don’t know anybody at S&W anymore that built the target or special product guns. I used to know a few of these mechanics pretty well and they would help guys like me with parts and a ‘heads up’ on things they saw coming down the pipeline. With the older guns there were variables on almost all the parts and even the frames were something you had to adjust and work with. In fact the term often used was an accumulation of tolerances
which was a clever way of saying a lot of play or slop from inconsistent parts. Ron Power was an amazing mechanic and a guy who could pop a side plate drop the guts and tweak it all into a lock work that was tight yet butter smooth. He was not just a gunsmith but more so an innovator who shared a lot of his ideas, techniques and tooling/fixtures with the Smith & Wesson factory. The real deal.
Let me just add — Google and Kuhnhausen don’t have it all — there is more