其实Blondie并不仅仅是凭借枪声的音色判断出来的,主要的辨别依据是Tuco独特的开枪习惯。下面这段话复制自IMDb,做出了比较全面的解释。
Tuco always shot with the same cadence/pattern/tune The "tune" almost certainly refers to Tuco's characteristic pattern of firing. He fires five shots in rapid succession, then, after a pause, the sixth shot. This 5:1 pattern is emphasized in the original Italian script, but it was not strictly adhered to during shooting. For example, at the gun shop, he fires at the Native American target figures 5 times, then after a pause, the sixth shot. Also, he should have shot Blondie's water canister 5 times, then a sixth shot. He also should have shot Al Mulloch 5 times, then stood up and released the final shot. Blondie hears "bang, bang, bang, bang, bang---long pause---then bang" and thus recognizes Tuco. This gives him a chance to slip by Angel Eye's men and team up with Tuco to slightly even the odds in the battle with Angel Eyes. And Blondie doesn't actually say "Every gun has it's own tune...". This is what Mickey Knox came up with for the looping dialog after there was a flub in the sound effects on the English language print, what was actually filmed was when Clint is with Angel Eyes and is playing with the kitty is "Five to one makes it easy. That's a perfect number large one" which was dubbed to "Every gun makes it's own tune, and it's perfect timing large one"