Reloading for the 1891 Carcano, Part 2

[Patrick Chadwick]

With regards to the deep firing pin impression on the primer, what is the correct extended length of the firing pin?

The "Atlante del Materiale d'Artigleria" specifies:
Length of firing pin 21.7mm = 0.8543"
Length of firing pin hole in bolt body = 20.0mm = 0.7874
Protrusion of firing pin 1.7 mm = 0.0669"

Firing pin diameter 2.0 mm =0.787"
Diameter of hole in bolt body 2.2 mm = 0.866"

If you dismantle the bolt, it is easy to check these dimensions and draw your own conclusions.
Unfortunately, I cannot find any tolerances for these dimensions.

Based on my experience with other bolt-action service rifles, I would say that anything from 0.050" to 0.070" is fine, but 0.04" or less is likely to result in doubtful ignition, because the firing pin will push the cartridge fowards as far as the head clearance will permit, and above 0.080" could result in punched-through primers. Since the usable limits are determined by factors such as the head clearance and the extractor, I cannot give "absolute" values. Some cases where the measured values of large head clearance and short pin lead to the conclusion that it should not work, do in fact work because the extractor, rather than the shoulder, is holding back the cartridge enough for the primer to be detonated.


Patrick