Thanks Ian. I am now better informed. I had no idea it was possible to obtain such mounts - very useful too if one is alternating between open sites and a scope. I will keep this in mind.
Re the pellets, I discovered there were various types of JSB Exacts, ie Exact RS, Exact Diabolo, Exact Diabolo Heavy and perhaps one or two more. Can I ask which one you use, which suits your .177 45?
Many thanks.
Andrew.