Bullet size for 1891 Carcano

[RBruce]

I carefully drove a .280 cast lead bullet into the muzzle. The measurements where the lead was displaced are .671mm and .696mm, lands and grooves. Can you determine the bore size from these readings? If so, would standard 6.5mm bullets be likely to work in this rifle? --TIA

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[jmoore]

I carefully drove a .280 cast lead bullet into the muzzle. The measurements where the lead was displaced are .671mm and .696mm, lands and grooves. Can you determine the bore size from these readings? If so, would standard 6.5mm bullets be likely to work in this rifle? --TIA

Ummm, mixed "metaphors"? 0.280" ball converted to fractions of a millimeter? Let's hope it's 6,71mm and 6,96mm and not 0,671mm/0,691mm! Otherwise it's a squeeze bore rifle... 6,96mm would be roughly 0.274" which seems a tad large for a Carcano! Minor dia. at 0.264" is largish as well.

Expect groove dia. to run 0.266"+ to 0.269".

And unless you have a Cooey sporter, the usual 0.264" bullets rarely produce acceptable accuracy. It seems 0.2662" to 0.2678" is about the acceptable range of sizes that can be made to do reasonably well, provided the bore is good. The long military-type bullet bearing surface doesn't invite usage in rough barrels.

ETA: Ach, zo! Patrick Chadwick already gave you a good answer in this thread:

A Model 1891 to keep my 1898 Krag, 1891 Mosin-Nagant and 1896 Swede company.

Which is a good thing 'cuz it's way past my bedtime. And I'm too tired to be serious...

[RBruce]

OOPS. I did err in stating the measured size of the 7mm (.280) bullet. It was 6.71mm across the lands and 6.96 in the part forced into the grooves.

[Patrick Chadwick]

Well .671mm would be a real small bore. Firing leads from propelling pencils maybe?