[alvin]

No caliberation needed. When power is on, it displays "0". Never used an older model, probably because this new one being "digital" (a hi-tech term?), the effort on my side is minimum. The device can count up to 99 shots, and after each 10-shot group, I turned the power off and then turned it on so it can "forget" the previous group.

Another thing is regarding difference of hammer hitting force of prewar and 1930. As we've already known, 1930's main spring is stronger than previous variations, also 1930 has a longer firing pin spring than previous ones to offset the stronger main spring. Why did Mauser bother making this change? Stronger main spring can protect bolt stop better, but harder hammer hit must be offset so the firing pin won't pierce the primer. But 1930's hammer hitting force is still bigger than prewar.