My Nills Walnut Combat grips came in yesterday and I'm very happy with them. The feel is much better than either the stock grips of the Hogue grips I had on it before. And they are much much better than the Selle grips I tried.
The fit and finish on these grips is perfect. The finish is a matte oil base and is easy to hold even when my hands are slightly wet or sweatty. I hope to get them to the range this weekend to see how they work.
In this pic the M-28 is on top with the Hogue Grips.
And here is the same M-28 with the Nills Combat grips.
I love my M-28 "Highway Patrolman". When I bought it, it had the stock S&W target grips and also came with Pachmayr Grippers. I tried the Gripper and with smaller hands, I was pulling DA shots to the right. I bought and tried Hogue rubber grips, but didn't like the deep finger grooves. I finally bought Pachmayr Gripper Professional grips with the shorter trigger reach due to the uncovered backstrap. They are the best grips for me so far.
Good luck with your M-28.