Talk:.30 Carbine/Archives/2021/February

Incorrect case capacity

Running standard geometry calculations, the listed case capacity can not be verified.

Even assuming a consistent .308 in ( 7.62mm ) interior case diameter, a volume of 1.4 cubic cm, would only have a height of .287 inches ( 7.28 mm ).

Since the interior of the case is greater than .287 inches ( 7.28 mm ) tall, the volume of the case, must be greater than 1.4 cubic cm.

Gregory JH (talk) 01:24, 6 December 2020 (UTC)

https://www.rugerforum.net on case capacity of .30 Carbine. Oct 06, 2016

30 Carbine, volume rated in grains of water: 
Max case capacity = 21 gr 
Volume occupied by seated 110gr bullet = 4.711 gr (Speer 110gr FMJ .308" dia) 
Useable case capacity with seated 110 gr bullet = 16.289 gr 
[Useable volume] will change if different bullets or different bullet seating depths are used ... max case capacity will stay the same.

We are talking about the volume of a cylinder holding 21 grains of water. I've weighed water measured in a .30 Carbine case (empty, fired Privi Partisan case) as just less than 21 grains of water filled even to the case mouth. One cubic centimeter of water by volume = 1 gram by weight = 15.4323584 grains. 21 grains of water by weight divided by 15.4323584 is about 1.4 grams = 1.4 cubic centimeters. Take the diameter of the case mouth as .308 (7.82mm) and depth of case cavity as 29mm and calculate cylinder volume as "pie are square times length", get about 1,393 cubic millimeter rounded up to 1.4 cubic centimeter. -- Naaman Brown (talk) 20:43, 20 February 2021 (UTC)