The facts presented are primarily based on Myszkowski’s "The Remington-Lee Rifle,” rather than my own research. The conclusions, suggestions, and speculations are mine (and entirely my fault if they are way off base).
Early rifles were marked on the left upper receiver flat:
“THE LEE ARMS Co. BRIDGEPORT CONN USA, PATENTED NOV 4th 1879” and had “E. REMINGTON & SONS, ILION, NY, USA, SOLE MANUFACTURERS AND AGENTS” on the left receiver wall.
“Later” guns had the same E. REMINGTON marking on the left upper receiver flat, instead of the Lee marking, and “PATENTED NOV 4th 1879” on the left receiver wall.
A total of approximately 11,000 M1882s were made: Serial number range for Army trials guns should be between 8800 and 9900, and for other contracts between 8000 and 25,000. Calibers were .45-70 for Army guns, and either .45-70 or .43 Spanish for other contracts.
Probably the three most obvious keys to narrowing your rifle down would be the manufacturer’s legend, the caliber, and the serial number. In looking at your photos, I believe I see “LEE” and “CONN” on the upper flat, which would be consistent with an early M1882. I wonder if you have missed or misread one or more digits on your rifle—a serial number in the 2000s should fall in the range of the M1879 rifles, which, while generally similar in appearance, are quite different from the M1882. Not to put ideas in your head, but I would expect a four-digit serial number beginning with “8” or, more likely, “9.” I would use a jeweler’s loupe and strong light to check the number closely. It might help to swipe it with alcohol or light oil to help increase contrast. And, of course, use a nonfiring dummy to check caliber—or check visually: a .45-70 the chamber would have no “step” for the bottleneck of the cartridge.
As to the trial guns, the barrel should be marked “US VP” ahead of the receiver, and “DFC” on the left barrel flat. The receiver should have “US” below the legend (I cannot make that out on your photo) and “DFC” on the right receiver rail. I don’t have an M1882, but I believe I have seen DFC stamps on similar era guns, and it is quite small. The stock cartouche is described as a script “DFC” in a box, and behind the triggerguard there should also be a DFC over “P.” Also be aware that at least some of the Naval Brigade guns were reportedly assembled by mixing and matching parts—the surplus dealer’s 250 rifles yielded a total of 208 serviceable rifles for the Navy’s purchase.
I also note that there were reportedly thousands of new and complete Remington Lees, likely including M1882s, in stock at the factory during the 1886 bankruptcy, and it would be a strange thing if some of those were not still available in 1891-92, when the Navy was buying rifles for the Naval Brigade. So it would not be too much of a stretch to expect some non-Army trials (as in, non-DFC marked) guns with legitimate Naval Brigade markings.
Let us know what you figure out.
--DJ