A round file should not be required
This was discussed in detail prior to the great forum melt down.
The concensus of opinion was to leave the weld seam unfettled as it provides usefull grip for the poly bush.
I have used the same material on my own wishbones in conjunction with 3GE's poly bushes.
Fit like a like a glove & work as they should ( Not too tight, not too loose )
The trouble with reaming this sort of material is that it is all too easy to overcook things & end up with loose fitting bushes
