just some random thoughts on the bore and these two steels.
* it's common knowledge in the machining culture that under a microscope the finish from the two steels will be vastly different, even with the same micro number. Stainless steel often gives a pretty and shiny surface finish, but we can also get the samething out of chrome moly. Kind o depends on the final finish and hone job on the bore.
An easier example of this to see is the bore of an automobile engine. Try and get the rings to seat with a polished bore. Never will happen. Now take that same bore and run a hone thru it a couple times to break the glaze. Bingo we're good to go. Yet a rough hone job can take awhile to seat the rings. How does this apply to a rifle barrel? It's a cylinder with a bullet used to plug the bore. The brite and shiny bore will have much more friction even though it doesn't seal as well.
* I'm not sure about the heat expansion properties of chrome moly verses stainless steel, but it's a little different. Add to this the fact that almost all C/M steels expand and contract in a similar fashion. Stainless steels are different. Not talking a lot here, but a couple tenths might mean a lot.
* another issue is accuracy in machining. We've came a long way in working with stainless steel, just like we did with C/M steel. Just that SS came on later. Fifteen years ago, there was no way you could cut SS as accurately as C/M. Yet now days they're close. I have always found I could get the last couple tenths out of C/M verses SS, but kind of a moot point when your honing the bore to a finish size anyway. The amount of steel you cut when rifling the bore is minor and not enough to even begin to get excited about. Still there is some due to tool pressure alone. The real issue will come later, and few folks even know about it.
* SS still does change a little more under heat, and barrel steels are normally high martensitic making them even more prone to changing. C/M steels are still hot rolled ingots in the beginning. If you have a bore that is perfectly strait, and finish is the same; both types will change under heat. The more they change the more they hand out resistance to the travel of the bullet. Big diameter of course change less, but longer barrels tend to move more. Movement of the barrel thus reduces speed of the bullet a little bit too
gary
