A medium 3-spring stockman with a Turkish clip blade, likely a 1970s-80s purchase. Not really meant to be fancy collectibles but definitely more of a working man's knife with excellent Colonial steel. We've scared up some history on those knives over the years in the forum. I've been targeting clean examples of Colonials/rebranded knives with those same synthetic stag handles as your grandfather's.
This particular thread explores the shared heritage of Sharp-branded knives that were sold in K-Mart. You'll see a version of the same knife in its original packaging here: viewtopic.php?t=51203
This one shows a range of Colonial-made Sabre USA knives using the sawcut handles instead of the "fake stag" composition: viewtopic.php?f=87&t=33434&p=587016&p587016
For my part, here are a couple of my posts (including photos) about these knives and similar ones:viewtopic.php?f=2&t=44545&p=679912#p679912viewtopic.php?f=87&t=32528&p=546893&hilit=colonial#p546893
Your knife should be a treasured part of your collection because of your grandfather's ownership and all the stories it can probably tell. Happy hunting!