Schilke 13A4a vs Stork CM3
The Schilke 13A4a has a wider cup diameter, the Stork CM3 features a deeper cup.
Cup Diameter
The Schilke 13A4a has a cup diameter of 16.76 mm / 0.6598 in compared to 16.30 mm / 0.6417 in on the Stork CM3 — a difference of 0.46 mm / 0.0181 in. A wider cup generally produces a fuller, darker tone but requires more air support.
Cup Depth
The Stork CM3 has a medium cup while the Schilke 13A4a has a shallow cup. Deeper cups favor a darker, richer sound; shallower cups provide more brightness and easier upper register.
Throat Diameter
Throat diameters are essentially identical at 3.66 mm / 0.1441 in, so resistance feel will be comparable.
Finish
The Schilke 13A4a is listed as unspecified, and the Stork CM3 as Silver plate. Finish mainly changes lip feel, tarnish resistance, and appearance rather than cup geometry.
Which is better?
Neither mouthpiece clearly dominates the other — the right choice depends on your embouchure, playing style, and the sound you're after. Try both if possible.