WS1/WS2 vs IC/WS2? Probably splitting hairs. Both likely are about perfect for grouse/WC cover. What gauge? WS1 in a 12 is often pretty close to IC, anyway. In the 20 or 16 WS1 will usually be just a bit more open than IC...but not alot more open.

WS2 is usually about a light mod in 20, 16, or 12 - and a great all-around field constriction.

Choose the gun you like better.

Sam