I recently purchased a Colt pre 70's Government model but it came with damaged hammer and sear (owner tried to get really light trigger) so the hammer and sear will have to be replaced.
I have a set of untouched hammer and sear from a 80 series Colt Officers model that I have left over after fitting some new parts on it from a while back. Can I use these hammer and sear on my pre 70's pistol?
Yup.
Absolutely. The Hammer and sear are not "80" specific.
The Series 80 hammer is interchangeable, but it doesn't have a true, captive half-cock notch. The quarter-cock shelf does the same job in stopping the hammer in the event of a hammer hook failure, but if the tip of the sear should break... depending on how much of the tip is lost... it can allow the hammer to contact the firing pin. Whether or not it will be with enough force to light a primer again depends on where the sear breaks. The liklihood of it breaking far enough down to fire the gun is pretty slim... but still possible.
For this reason, I don't advise carrying it cocked and locked without a safety strap between hammer and slide.
Another thing to be aware of is... just because it made for a super trigger action in the original gun is no guarantee that it'll do it in another gun. You could wind up with anything from a hard, gritty action to a crisp, sweet one to a 38-ounce, .45 caliber sub machinegun with a 1500 rpm cyclic rate.
Is this any different than what Colt is now doing with their New Series 70 pistols? Arn't they installing 80 series hammer/sear to their 70 Series pistols?
.45 Shooter... Yep. I don't advise carryin' those cocked and locked either.