Looks like you've got somebody's project rifle.
An Oberndorf (42) K98 action. A Colt marked Jefferson barrel, probably bought from Numrich or some other parts wholesaler. I can't ID the stock as any particular maker...that roll-over has a unique profile but not one I've seen before. Are there any markings on the recoil pad?
A genuine Colt 57 would have a regular commercial FN action. They didn't use any surplus K98 actions on em. AFAIK, they were only made for one or two years. 1957 or 1957-58.
No stripper clip hump and no thumb cut-out on the receiver, a swept-back bolt handle with one checkered flat on the bottom. Basically they look like any other commercial FN action.
The stock also wouldn't have the large roll-over cheekpiece either, just a small ambidextrous MonteCarlo cheekpiece with no roll-over. They should have a black Colt-marked buttplate also...no recoil pad.
I've seen three in person (one guy owns two). The stocks on those three are checkered and uncheckered, so they might've had different price grades.
Too bad, because a genuine 57 would be worth pretty good coin to a Colt collector (or a Mauser collector too I suppose).
Jim beat me to the punch. I was digging through my picture folders to see if I had any of the one guy's pair...can't find any pics.
Here's one on a Cabelas listing that is typical of the three that I've seen. http://www.cabelas.com/colts-colt-mo...43-win-1.shtml