Well, they say the best is THE BOOK OF COLT FIREARMS by Robert Q. Sutherland and R.L. Wilson. Wilson has a web site you can check out.
But unless you have a large chunk of change you won't be buying one.
1st off they are apparently no longer in print. 2nd is they are very pricey, as in up to $500!
The 1st edition I guess has become sort of a collectors issue. I believe these have a copyright date in 1971. A reprint was released I believe around 1985. Either way the info is great but does not include any of the more modern stuff.
Unfortunately I know of no other single good resourse covering strictly Colt DA revolvers.
I recently purchased a new 2nd edition BOOK OF COLT FIREARMS by Robert Q. Sutherland and R.L. Wilson for $150. There are deals out there but it is getting increasingly difficult to locate 2nd editions therefore the prices will be driven up. 1st editions are going for $500.