[Par71]

Since #1 is used, does it become 4 barrel? And since 4 Barrel is a hitting procedure, it becomes 4 barrel hitting?

Or it means using #1 passively (not actively for straightening the right arm), it still a 3 barrel therefore swinging?

4 Barrel is not necessarily Hitting. A Swinging Procedure can also be 4 Barrel. Homer Kelley had a sample pattern for a 4 Barrel Swinging Procedure in the 3rd edition of the book.

Accumulator #1 participation in a 4 Barrel Swing is active direct drive at PP#1. That's what the "except per 2-M-3" at the end of 10-11-0-1 tries to express.