Why do we buy 300# anvils? Because more weight under the hammer makes for easier more efficient shaping.
Horizontal RR anvils work great for light duty, thinner metal shaping.
Here is a way to maximize RR rail for heavier work.
Use a 30" of so length of rail, set it on end down into a five gallon bucket of premix concrete, then source out a piece of 2x5x5 flat stock and weld it on the top end of the RR,
or what ever size suits you, the thicker the better.
Even mild steel takes a lot of abuse and when it gets too dinged up, grind or draw file it flat.
Beginning knife makers use this set up to get started.
Anyway, nice looking anvils guys.
Nuts