2 Attachment(s)
Reloading for the 1891 Carcano, Part 2
After reading previous advice on loading the 6.5x54 Carcano using Hornady 160 gr. .2675 bullets, I pulled the bullets from the rounds I had trouble with before. Using the recommended chart, I loaded ten rounds, carefully measuring each power load and seating the bullets to the correct COL.
The results were surprising. The first round went off OK, although the bolt required more than normal effort to extract the case, but not a great deal more than normal. The second round went off, and I don't think it was louder than the first, however immediately smoke was curling up from the receiver around the bolt. I did not feel any gas on my face, but was surprised at the smoke.
When I tried to extract the spent case, the bolt would not turn. By using the top of the wooden shooting bench, I was able to rotate the bolt and pull it back. The case remained in the chamber. The primer fell out on the bench with a hole burned through it. I had to use a cleaning rod to remove the case.
Note: The bore and chamber had been cleaned prior to firing. Four rounds of 140 gr. Nosler Partition bullets have been fired first. In the photos, the left case is the bad one, and the middle case is the first 160 gr round fired. The right case is from the Nosler 140 gr. round.
Needless to say, I am going to stick with .264 bullets for the rifle. I did fire ten rounds of 160 gr. Hornady .264 bullets after the incident. I had no problems with them.
Carcano firing pin dimensions
Quote:
Originally Posted by
RBruce
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.
:wave:
Patrick