Quoted:
This one came like that I usually see the stainless with the arched mainspring housing either way you probably have to change it out since its plastic, I prefer the straight myself, I think it would resell itself easier since it doesn't have the 100 year roll mark, which most of the ones I've seen do.
Very interesting. Honestly, I've never seen a NIB S70 with a flat MSH, blue or SS. (Colt's catalog and website show both with the arched housing) And I also thought that all the S70's came with steel MSH's, as mine did. The S80 guns do come with a plastic MSH and I've changed mine to steel parts. Is there ANY possibility that someone changed that one to a flat plastic housing before you bought it? I'm far from a Colt expert, so I gotta ask.
I agree that the absence of the 100 year rollmark may re-sell quicker, for now anyway. Seems to be kind of a 'love it or hate it' sort of thing. I bought mine this year specifically for the rollmark.