Date: 1937. Image by VintageSax
In the 1930's and 1940's instruments with the "Connqueror" name were Conn's best models.
The issue of mouthpiece selection for the 30M in relation to intonation often comes up in various forums. The consensus appears to be that the 30M is quite mouthpiece sensitive and works best with a mouthpiece that has a large, round chamber. This is in accordance with the type of mouthpiece most in use at the time.
What Conn said in 1941:
No alto or tenor saxophone can do for you what these Connquerors will do. These instruments are the finest ever built. Over a period of 50 years Conn has developed Hydraulic Expansion, drawn and rolled tone hole sockets, adjustable pivot screws, new octave socket, fact octave mechanism, G# trill key, Res-O-Pads - all of them patented and exclusive on Conn altos and tenors. Exclsuive on Conns also are longer cross hinges, the hard durocast keys, and reserve power. On the alto are found the tuning device, and the bottom mouthpipe key, both patented and exclusive. On both is the Conn patented raised E key. No other manufacturer has contributed near as many improvements. In fact, Conn has contributed more than all others combined. And now, added to these features found on the Standard models, we give you these important additional features on the Connquerors: Permajust action; new table keys for G#, C#, B-natural and Bb; further improved and faster octave mechanism; heavy silver inlay on 14 keys plus thumb hook; and rose mat engraving. With the silver inlay keys everywhere the hands touch is either silver or pearl. [...] On the alto you have the patented "underslung" design [of the mouthpipe key], very sturdy and in protected position. The tenor mouthpipe key is of new design with extra long hinge and tempered strap brass, more positive and sturdy than the wire type. Designed for the modern player and built for years of trouble-free playing satisfaction. Steelay mouthpiece standard.