Different guns use different cylinders that have different number and position of openings. Let’s look into the number and position issues separately. Talking about the number of openings (also known as auxiliary ports), there are many arguments supporting the use of multiple evenly distributed openings (such as smoother compression, stabilized air flow …etc).
Frankly, the difference between one bigger opening versus multiple smaller openings isn’t that significant in a real world context. We do see a direct relationship between the position of an opening (how far it is from the cylinder head) and the barrel length. Ever wonder why all TM AEG models can achieve almost-identical muzzle velocity even with different barrels? The key is the positioning of the cylinder opening.
A proper cylinder configuration should be able to accommodate sufficient air (and enable efficient compression) so the bullets can be successfully propelled out of the barrel while maintaining the targeted velocity. When the barrel is long, the cylinder should have no aux port on it.
