General slingshot card ball is how big!

Card ball generally have 4.5MM, 5.5MM, 6MM three, the vast majority of bows with 4.5MM, Thunderstorm, Sniper Tiger, Tomahawk IV and other these with 5.5MM, Sniper Eagle full series with 6MM. leather ribbons vary in thickness, there are 2050,1745,2550,3050,3060, etc., the first two that the inner diameter, the last two that the outer diameter. The eye of the bow is big at one end and small at the other end, and it can't be pulled out after the ball is stuck in the leather band. If you can pull out, either slippage, or the wrong card ball, change the larger card ball on the line.