Single strand slingshot and double strand slingshot which muzzle velocity fast

1\If both the single and double strands have smaller steel balls, then the initial speed of the single and double strands are very close or the initial speed of the double strands is slightly higher than that of the single strands;

2\If both the single and double strands have small steel balls, i.e., very small balls, then the initial speed of the single strands is slightly greater than that of the double strands;

3\If both the single and double strands have large steel balls, then the initial speed of the double strands is greater than that of the single strands. With the increasing of the ball, the initial velocity difference between the double strand initial velocity V1 and the single strand initial velocity V2 (V1-V2)) is getting bigger and bigger.