Colt 38DA means that it is a .38 Long Colt caliber, NOT .38 S&W Special. Guns in that caliber had 0.375” grooves in the barrels. They shot 0.375”OD heel-base bullets with external lube. The chambers were drilled straight through the cylinder without a smaller throat towards the front of the cylinder like present guns have. Later, the cartridge was changed to a hollow-base bullet that was 0.357”OD and placed entirely within the case (internally lubed).
The latch is normal for that gun up until approx. 1909. The change over to the one used more recently was made about that time along with several internal changes. The serial number would tell exactly when it was produced. There are several places that provide that information on the Internet.
I had one like this (but with fixed sights) that was made in about 1902. I also used Federal .38 Special hollow-base target wadcutters in it. This was long before CAS shooting made cartridges available again. The hollow-base expanded to fill the barrel to give reasonable accuracy and it was downloaded enough that it did not damage the gun. I have heard that sometime between 1902 and 1909, the groove diameter was reduced to 0.357”OD like what is used in the .38 S&W Special, but I have not been able to confirm that myself.
Slug the barrel and check the serial number to find out exactly what you have. That will pin down most of the information you need. Have fun shooting it. I have several of that model, but most are in .41 Long Colt.
Does the ejector rod on your gun have a end similar to this one?
Thanks for your informative comments.