The SAS3 kit does not use the whole original cocking handle. Due to the striker-fired design, it uses a truncated handle. You can just trim an original MkV handle like will come with your kit, but a better solution is to use a repro MkII cocking handle to match the fact there will be no cocking handle safety hole on a SAS3 receiver tube. An added advantage to making a (very hard to find and rare in original form) MkII handle is that you can fit it precisely to your bolt so its does not wobble around on you.

You make one on a lathe and will need a knurling tool.


And here's a couple we made up compared to a real mkII handle: