1906 FE-Grade Trap Gun --

1906 CEO-Grade 12-gauge --

1905 DEO-Grade 16-gauge --

1896 AE-Grade 12-gauge --

1906 KE-Grade 12-gauge --

1909 KE-Grade 16-gauge --

And, here is my 1895 vintage BE-Grade which is marked B J E --

The B and the E could signify grade and ejectors, and the barrels are the Chain Damascus pattern which on the Remington Salesman's sample of Damascus patterns was called Chain J.
Charles Semmer showed a page of these various marks in his book RemingtonDouble Shotguns, but very likely there is no one left alive that really knows what these marks mean.