Failure to feed in my Husqvarna M38

[Patrick Chadwick]

Is the oval one on this page the one you mean?

I would personally prefer to use a flat one in this case. The cutting surface is slightly flexible (because of the plastic backing) so that you can actually get the tip of the flat lap to follow a gradual curve. The curve along the receiver cutout rim is so gradual that with the oval one you may go in too deep and actually cut a slight depression. However, the rate of cutting is soooo slow that as long as you frequently wipe off the oil to check progress, you are unlikely to make that mistake. So either will do the job. Your worst enemy is impatience.

I have over the years acquired a number of these tools - flat, round, and oval. The oval one is excellent for sharpening knife blades to an almost razor edge. The flat one is invaluable for touching up burred trigger edges and the like, without cutting through case-hardening.
But remember - these are not metal files - they are only for removing tiny amounts of metal - so always use a light touch and a drop of oil. Fairly thin oil, as you want the microscopic swarf to float off the surface, not clog the cutting surface.

Patrick