There have been a number of adaptations of the M14 bolt roller retaining ring installation tools over the years, mostly made by grinding down pliers of different shapes and drilling the proper hole for the bolt roller shaft. I have made a bunch of these and never quite found one that would work the way I wanted it to. Always seem the smooth surface in the hole would allow the clip to slip out just as I was trying to put the roller into place.
Soooo, in the middle of the night a number of years ago after installing a pile of clips, I came up with an inexpensive solution that works perfectly for me.
Took set of small locking hemostats , warmed the jaws and formed them around the proper size drill bit. Now, easy squeezy, slip the clip over the bolt roller support into the recess and clip the tool in place and lock. That frees up that spare hand that has been trying to hold the clip. The bolt can be held in one hand the the roller pushed into place with the thumb. The serrations on the inside of the jaws hold the clip wonderfully.