"J for the barrel material?" Researcher may be correct
Remington had one 'J' and several 'SJ' patterns, and I have no definitive answer as to whom 'J' or 'SJ were
NAMED PATTERNS used by Remington were London (Stub Twist), Twist, Laminated, Boston N. (Horse-shoe pattern), Boston 2 S.J. (2 Iron Crolle), Oxford 2 & 4 S.J. (2 & 3 Iron Crolle in several different patterns), Chain J, Etoile 3. B.P., Legia P. (Herring-bone pattern), Washington N 3. B.P. ("Stars & Stripes" or "American Flag Bunting"), Chine P ('mottled'), Ohonon 6 S.T., and Pieper P.
The Remington Damascus salesman's sample rod is shown on p. 275 of Charles Semmer's
Remington Double Shotguns.
Remington damascus barrels with possible Belgian maker's marks include 'HP', frequently found on Oxford 4, likely Henri Pieper. Pieper had a separate barrel factory in Nessonvaux. Oxford patterns are used from the Model 1876 to the 1900 KED.
A grade and Etoile pattern 1894s are found with a fused 'JP', possibly the mark of J. Pire & Cie, a large munitions firm established in Liege in 1885.
The significance of 'S.J.' (Boston 2 and Oxford 2 & 4) is uncertain, but could be Simonis-Janssen. Albert Simonis, J. Janssen & Demoulin Fils was established in 1883 and used the mark 'S.J.& D.'
The meaning of 'B.P.' (Washington N and Etoile) is unclear. Claude Gaier's "Four Centuries of Liege Gunmaking" states that Ernest Heuse-Lemoine of Nessonvaux named both "Washington" and "Boston" patterns for the US market. Boston N. and Boston 2 first appear on the Model 1878. Washington patterns are also found on Lefever and Ithaca guns.
There were at least 20 different Belgian companies that operated under the name Thonon from approximately 1836 to 1941. At least one, Fernand Thonon & Co. was the proud distributor of arms to courts of Italy and the court of the Grand Duchy of Luxembourg.
More here
http://docs.google.com/Doc?id=dfg2hmx7_72xs856hdf 
