Bishop Steiner, on 26 October 2015 - 03:52 PM, said:
The first mention that it might not be a stock RFL-3N was in the Solaris 7 Box Set published in 1991. It espoused several theories, from being built with star league tech, post discovery of IICs, it was theorized it might have been an 80 or 90 mech, etc.
The only actual canon description of it, in Warrior: EnGarde, was of a stock rifleman armament (5 shot popguns), (paper thin) armor, ammo loads and gross heat burden (when he triggered the large lasers, the wash of waste heat had him comment on it not being an efficient machine). Justin Xiang gives a running commentary of all the mechs shortcomings throughout his match against Philip Capet. Also, nothing was unusual to the eyes of a master technician, Tsen Shang when he prepped it for Justin's use for the title match.
It being anything else, is to the best o my knowledge, unsupported rumours.
Of course, in MWO it could be armed however you like.
The fact that it managed to not only compete but win in the Class 5 (which is utterly dominated by assault 'Mechs considering it's the only non-Open class they can fight in) arenas for seven years running pretty much points a big flashing sign towards the lostech version. As of 3052, the top 20 on Solaris had one heavy. And it was a refitted Marauder, with the remainder ranging from 80-100 tons.
The "Legend-Killer" Justin fought in was very likely a ringer- and the "real" Legend Killer" was never found. Given the preponderence of lostech Noton's original 'Mech may very well have ended up mothballed somewhere for lack of parts, considering Noton's retirement without a single loss in seven years against a string of assault 'Mechs (where he was the only "heavy" to compete.). The Solaris VII sourcebooks indicate there was evidence that Noton's 'Mech had actually tonnage in the 80-90 weight class....which points straight towards the Royal version. And such a beast was going to be very, very well hidden even (and especially) if it was a Star League lostech chassis.
Note that Class 5 arenas don't check weight- since it's "assault or lighter"- and there is no such thing as a "pre-match check" on a 'Mech unless specific conditions are required (like melee only). (Again, Solaris VII sourcebook- the Marauder in the top 20 is specifically noted as having plenty of secrets other stables would pay to know- and if such an inspection existed from "refs", the info would have leaked.). In fact, if he'd competed in Class 4, there WOULD have been weight checks to insure he wasn't piloting something too big- and a Rifleman II would have failed miserably.
Once you fill in all the lines, it's obvious regardless of not being stated outright.