I guess they all used Mauser actions until the magnum actions became unavailable. I think some Enfield actions were used by H&H. I have seen photos of them but don't recall seeing one in the flesh. They used Mannlicher actions too i think? Rigby bought theirs barreled from Mauser.

Do any use GMA actions? I seem to recall one maker using them at some stage.

I really like the look of the new Rigby rifles, especially single square bridge with H&H pattern scope mounts.