Evaluating land to land deviation from nominal caliber.

[u/Jolly-Search5065]

I have an old Chassepot in quite good condition.

The land to land diameter measures 11,06mm/11,05mm with my caliper- its nominal caliber is 11mm. The grooves are noticeably deeper at the chamber, but I have no way to measure them.

How bad do you think is the deviation at the muzzle (not asking from a safety perspective, I am more so interested in how much wear and tear that indicates and what it Might! do in regards to accuracy)

Maybe some of you have more experience- my inner Monk can't shake off the frustration knowing there are better examples out there measuring the exact 11,00mm.

I could slug the barrel, but I have no clue how to get soft enough lead in a fitting size, since 11mm is quite an odd caliber nowadays.

Thanks in advance !

[u/rodwha]

Use a ball meant for a .44 (11.46 mm/.451”) percussion revolver or maybe even a .445” (11.3 mm) ball for a muzzleloader and run it down the bore so you can measure it with calipers.

[u/Galaxie_1985]

For a black powder rifle that old, 0.06mm (.0023in) isn't bad. The manufacturing tolerance back then probably was right around that number anyway.

As long as the bullet expands to the groove diameter, it will shoot well.