I have a Vickers in .242 . In the 1938 Parker Hale catalogue, the rifle is called the Vickers .242 magazine express rifle. I will look at my 1924 and 1930 Vickers catalogues when I return home tomorrow. I recall that they simply call it the .242 express. given that the only manufacturer that used this calibre was Vickers, I'm pretty comfortable calling it the .242 Vickers.

Re the 117gn Hornady. a friend gave me a packet of these projectiles in a very old box and a packet of Winchester 117 in an even older box. I resized like Mike. (huge thanks to Mike for sourcing the resizing die for me) and both projectiles have the same point of aim. In my only range outing to date, they group around 3/4 inch at 50 metres. I'm back to the range with the Vickers in a coupe of weeks to sight in at 100m and then I have three days planned hunting Fallow Bucks so it will be interesting to see how the 117's perform.
My velocities to date are around 250 Savage velocities.
My Vickers had its receiver drilled and tapped and we found a Redfield Jnr to fit perfectly.
Its a beautifully made rifle in a calibre that almost guaranteed its failure. cheers hendo