I see alot of scope rings and bases are made of 12L14,and left unhardened(I'm assuming since they don't look case hardened). But I know some custom rings are hardened steel. So what should I use for making a set of rings and bases of my own? Just use cold rolled or should I get some 1045 or 4140? Same question applies to bottom metal Just use cold rolled low carbon or should I use something I can harden? Any opinions much appreciated.

wanna,
1018/1020 is fine for this...
jeffe

I'd go with 12L14 or 303 s.s. I really hate 1018 or 1020 CRS, too much residual stresses in the material.
Just my opinion......

Jay,
i can agree with that... so go with hotroll?

iirc, 12L14 is leaded... which I don't really want to machine in my shop... even though it turns VERY nicely

jeffe