Jeweler's rough comes in different grades depending on how much you want to remove via polishing.
JB Bore bright is the same stuff already graded for gun use. The gray is a bit more harsh and the red does a bit less polishing. In cleaning a bore or cylinder, you use the gray if it is pretty rough or the red if you have already lapped it with the gray or you have a new gun that should theoretically be clean.
Regarding fixing old firearms--S&W is a business that manufactures and sells firearms. The parts and repair business is a sideline necessary to help them sell firearms (and the parts come as a byproduct of manufacturing them). As firearms age just like every other mechanical device, they often need repairs on parts that commonly wear or those parts accidentally damaged by the user. They also have warranty claims. At a certain point, a model stops selling, the parts to repair them are mostly sold or used, and the inventory carrying costs get too great. They then sell the remainder of the parts to places like Numrich or Sarco.
Most people never think about where the parts come from but they have to be manufactured and then stocked into a warehouse. During that time, the machines, tooling, and even how the part was made and functions within a firearm fade, it also costs a bunch of money to keep a parts warehouse going--both in labor and inventory carrying costs (warehouse, insurance, utilities, inventorying, spoilage, and property taxes). Smith and Wesson is not going to reopen an assembly line for parts on a revolver last made in 1945 (let's say a Victory model)-they likely do not have the machines, tooling, the technology, nor the workers to reproduce the parts which will cost a lot to replicate. What's worse is that these parts were often then handfitted to some extent (to a great extent for Colts) to a particular revolver--they are not mostly drop and fit. So even if they could make the parts, the parts would require handfitting by a craftsman familiar with the Victory model. At the same time, they would also be competing where a bunch of old parts are out there in parts warehouses or through junking old firearms which would hold the prices received for the parts down. There is no way to make a profit.
Imagine complaining about your Ford dealer because they will not service or provide parts for your Model A as an example.
To that end, S&W will give technical support to individual gunsmiths to let them take on these headaches and a good gunsmith can make and alter/fabricate/reuse parts if necessary to individually fit a firearm.
As a side not, while people are cursing the MIM process, on the flip side, molding technology is easier and cheaper to make small runs rather than the old style forging and machining. Done right, it can also have tighter specifications thus lessening the old handfitting problem. It just might allow for parts to be made in small batches to do warranty work for a longer period of time on a number of firearms.
Direct from the horse's mouth,
"Smith & Wesson’s Lifetime Service Policy begins after the warranty period has expired. Smith & Wesson will repair, without charge, for the lifetime of the original owner, any Smith & Wesson handgun purchased on or after
February 1, 1989, and any M&P15 series rifle, that is found to have a defect in material or workmanship."
https://www.smith-wesson.com/customer-service/warranty
Note: the warranty only applies to defects in materials and workmanship--not ordinary wear and tear or abuse. They do no promise to fix any and all Smith and Wesson firearms either nor to provide parts for them.
Ruger does not have a written warranty for example and people have been upset with them too--one example with when the original firearm had a forged part and it was replaced during service with an MIM or cast part.
Have a family heirloom, go to an excellent gunsmith or a reputable shop such as Cylinder and Slide, Turnbull, etc. and pay the man for his time, possible fabrication of parts, and fitting labor. Expect that it will take some time--good ones almost always have a backlog. A good one will also tell you the truth--in some cases, any repair will have to be made by a high priced specialist in restorations--Doug Turnbull, etc. and might never be able to be fired again--some damage cannot be fixed so as to safely allow firing it again.
