I got a reproduction handguard (second hand) for an 1898 that has no clips, nor holes for rivets. 

Not having an original to examine, I'm not 100% clear on what the exact curvature of the clips should be, or radius as compared to barrel diameter.  I assume they are a basic "C" shape,

I suppose my two questions are...

First, I assume they are more than 180 degrees of a circle, and so about how much of an actual circle are they?  Closer to 225 degrees?

Second, is the curvature circular to match the barrel, or is it a tighter radius such that the clips will "pinch" the barrel?

What I wish I could find is a photo of a handguard from the end to show the clip curvature clearly.