45 front ring ~ calling RH

[Bally]

Thanks for the reply Manglier and for taking the time to link a photo.
I had considered this as in my post above:

I could elongate the slot but there will be a point where it may become a flaw and fail

I've had another look and there is 4mm of metal below the slot so I would have to remove all of the metal to make it an open slot, something I don't fancy.
.
Glad yours works and at least it isn't just me!