Forgive my ignorance, but are the Enfields and their clones rifled????
As Hawg pointed out, yes, the Enfields and the modern clones were rifled.
I don't think Euroarms or Armisport had/have progressive rifling. From what I'm gathering from Google, the Parker Hales did have progressive (gain twist) rifling.
There are two kinds of "progressive" rifling: progressive twist (gain twist) and progressive depth.
As I understand it, progressive twist, or gain twist, means that the rifling starts off slow and spins up as you go along the barrel. The idea is that the bullet will not strip against the rifling when it first starts its forward linear movement.
Progressive depth means that the grooves start off deep near the breach but get shallower and shallower towards the muzzle.
Whitacre makes replacement, competition barrels for Enfields, and his website says they have progressive depth rifling.
Many reproductions and replacement barrels have different twist rates than the original Enfields, which were 1:78. My Whitacre is 1:72. Euroarms says 1:78, but I have been told they are 1:72. Not sure what Armisport is.
Edit: Oops, got in too late!