I just checked my pair of 7 1/2 inch 1851s, an 1851 Navy Sheriffs model, and an 1862 Pocket Navy. All four have magnetic barrels, hammers, wedges and screws. Magnet will not stick to frames, backstrap, trigger guards or cylinders.
Hi Fingers, 300 series stainless steel is austenitic, non-magnetic, extremely tough and ductile. 410 Stainless Steel is a martensitic magnetic, stainless steel that provides good corrosion resistance plus high strength and hardness. Seems that your revolvers are a combination of both SS series.
I remember years ago that when Colt began to use stainless steel in some of their pistol models that the machinists would call in sick when a stainless steel run was scheduled. Seemed that they were using the 300 series stainless that is gummy and difficult to machine. It was hell on tooling, defects, and operators. That situation is better today in that there is available free machining stainless steel.
I have modern stainless steel handguns and even one stainless 1858 Remington. Some of my stainless steel .45 handguns photos:
Regards,
Richard