If you aren't satisfied with the expert help here, you might go over to the Colt forum and ask for help from member "DACOLTGUY".
He's Robert Best who is THE expert on the Colt New Army & Navy revolvers.
He wrote the standard collectors reference book on these Colt's.
http://www.amazon.com/Pattern-Doubl...JOY_1_1?s=books&ie=UTF8&qid=1441764525&sr=1-1
The Colt forum:
http://www.coltforum.com/forums/forum.php
Here's a little info on your Colt.
In 1889 Colt introduced the world's first double action, swing-out cylinder revolver.
This was the Colt New Navy of 1889.
In 1892 the US Army also bought it and it is usually known as the Colt New Army & Navy series.
Colt put the design through a rapid series of improvements including 1889, 1892, 1894, 1895, 1896, 1901, and 1903.
Production ended in 1907.
These were available as US military issue and commercial civilian sales guns.
The military versions were chambered in .38 Long Colt, had smooth wood grips, six inch barrels, and had US Army or Navy stamps on the butt.
It was the Colt New Army in .38 Long Colt that failed in the Moro War in the Philippines and led to the development of the .45 Automatic.
The commercial versions were available in 3 inch, 4 1/2 inch, and 6 inch barrels.
Calibers were the .38 Long Colt, and the .41 Long Colt.
Very late in production they were chambered in .32-20 and .38 Special.
Grips were hard black rubber with molded in checkering and Colt logos.
ON ALL GUNS THE SERIAL NUMBER WAS STAMPED ON THE BOTTOM OF THE BUTT IN TWO LINES.
Some guns were stolen from the military and others were legally purchased as surplus but owners were afraid the US military stamps would be thought to be a stolen military issue gun so people sometimes ground the serial numbers off.
Since the butt was perfectly flat, removal of the numbers and any US stamps was easy.
Because it was too easy to remove the serial number, in 1908 Colt moved serial numbers of new model revolvers to the inside of the frame under the barrel.
There are other numbers on some parts. These are factory assembly numbers used in the Colt factory to keep fitted parts together during manufacture until the actual serial number was assigned and stamped on the butt.
Once the actual serial number was stamped, the factory assembly number ceased to have any meaning.
If the gun is in the original factory assembly condition, all the assembly numbers will match.
Mis-matching numbers means parts have been replaced.
Note that most of these guns were actually chambered for the obsolete .38 Long Colt. This IS NOT THE .38 SPECIAL, even though the .38 Special will chamber.
If the gun is shot it should be fired with modern Cowboy shooting type .38 Long Colt ammo, or custom hand loaded light loads in .38 Special brass.
UNDER NO CIRCUMSTANCES SHOULD IT BE FIRED WITH MODERN FULL POWER .38 SPECIAL AMMO.
These pre-1900's gun were not made of modern steels or with modern heat treating.
The gun should be treated gently.
These have notoriously fragile actions that break or get out of order rather easily.
Due to the complexity of the action and lack of any parts, repairs are pretty much impossible to get.
As for the finish.
The original guns were finished with the old Colt heat bluing process where specially prepared parts were put in steel drums and baked in temperature controlled ovens to turn them a bright blue.
Some parts, like the hammer and trigger were given a different heat bluing process and these are recognized by a brilliant mirror-like light blue color.
In your guns case, the finish is very obviously a much later type of blued finish done using a modern hot salts bluing process which looks much different then the original oven heat blue.
Note also that the gun shows very obvious signs of haven been polished by a less than expert polisher who rounded off the edges and corners that should be sharp and left ripples in the flat surfaces.
Bottom line:
Your Colt New Army & Navy model has been refinished with a modern type of bluing, and the serial number has been removed from the butt.
As explained above, it makes NO difference who removed it, when, or why, today, due to Federal and State laws, possession is a felony offense because under the Gun Control Act of the 1960's removal or defacement of a serial number on a gun that originally had a serial number is a crime.
Again, if you're not satisfied with the information given you here by some experts, go the the link I gave to the Colt Forum and talk to THE real expert, Bob Best who is the internationally recognized expert on these Colt's.