While nickel K-22's are not on my radar going to just put this out there for the guys to ponder,

First is that we have seen the small nickel run of 17-3's bring more than this 18-1 sellers ask,
Second is that while other models had the front ramp pinned to the base with factory nickel guns of that era,
the Combat Masterpiece seems to be an exception to the rule IMO.

Not casting judgement either way but if you scroll through the CM evolution you will notice by 1954 (post #34 in the thread)
It appears the CM has a ramp that is integral with the barrel.

Some Combat Masterpiece eye candy


If this is true the ramp and blade post 54 would have been nickel as well.
Since I have not seen another Model 18-1 not going to say either way but at this point am leaning towards it being factory nickel as some sort of special order.
I would definitely reach out to Roy before purchasing to confim authenticity or buy contingent on it lettering as shipping that way,
If the gun went back and was factory renickeled there would be no premium IMO.