Do some of you have photos of or know where I should polish my M98 action internally, to make them as slick as possible?

Polish where the bolt touches; it is intuitive; you can see where the lugs ride, and where the bolt body goes though. Not too much though because they are none too tight as is. Guys used to cut a slot in the bridge and weld it back, and tighten them up; not me.

To do a professional job requires a few made to order tools. I use aluminum bar stock milled to fit the rails and attach abrasives via double sided tape,

Where the body rides is a slam dunk with a 9/16" drum...The problem is that I can' find that size anymore..When my stash runs out, I may try rubber abrasives turned to size,

The tang bolt body recess will polish out nicely with a 3/4" drum.

Feed ramps and rails can be tackled with a Dremel tool and various abrasives. Done
right, everything is slick and looks damn nice.

Ted Blackburn used to tighten a REALLY loose Mauser by insetting a mandrel at the bridge. Heat the right-side and with a sacrificial scope base sort of crush the bridge in a v vise...Well...that actually works, but the bridge will need work to reestablish symmetry.


Same idea as dpcd mentioned, but saves welding

Of course DW explained it in a much more detailed manner.
Another way is to only use pre WW1 Actions that are already glass smooth. And not heat treat them as that makes them rough again....

I made my polishing mandrels out of hardwood. Taped the abrasive to them.

Dave

The more you polish and remove material the more loose the already loose miliary tolerances and wobbly mauser bolt with low contact area become.

Are you sure you need to polish?

On a full custom, I always polish the interior of the action..if only for appearance, I just remove bluing with maybe 400 grit