Try want ads, gun shows, gun shops.
Colt did not make the rifle. Sauer made it for them.
Try e-gunparts.com
Contact Colt, on line aucitons.
To remove the bolt from a Colt Sauer rifle, first ensure the rifle is unloaded and pointed in a safe direction. Open the bolt by pulling it to the rear, then locate the bolt release lever, typically located on the right side of the receiver. Depress the lever while simultaneously pulling the bolt fully to the rear to release it from the action. Once released, you can lift the bolt out of the receiver.
Contact Sauer.
Contact Uberti Customer Service through their website and get an owner's manual. You did not say what MODEL rifle you have.
Best left to a gunsmith
Price, the 92 costs more
You will have to call Sig Sauer to find out
What is the age of a Colt rifle serial SLD25319
I don't know how much exactly but a lot. The fact that it is from Sauer (now part of Sig-Sauer) and that it is a fine and now discontinued sport rifle will make it VERY valuable. Unless of course it is in absolutely terrible condition.
You will have to call COLT to find out.