Antoninus Pius sestertii with special edge

[Charles S]

Regularly I find a special type of edge on sestertii of Antoninus Pius.  There are perpendicular ridges at a rate of about 2 per mm, too wide to be file marks .  It is a bit like a serrated edge but not immediately noticeable.  Here is one example of such an edge with markings.  It is from a coin I just got in and uploaded it to : https://www.forumancientcoins.com/gallery/displayimage.php?pos=-114996

Is anything known about these type of edges ?

[SC]

I don't think the marks are too wide for a roman period file or rasp.  It looks like it may have be the remains of an attempt to file down the spur from when the flan was cast. 

Shawn