In larger cartridges like the .308, while larger magazines do exist, 20 rounds is the typical standard capacity due to the size and weight of the magazine. A loaded 20 round magazine of .308 weighs more than a 30 round magazine of 5.56mm. read more
In addition to the most common factory derivations, the .25-35 Winchester, 6.5×52mmR, and the less-well-known .219 Zipper, the .30-30 has also spawned many wildcat cartridges over the years. One example is the 7-30 Waters, made by necking the .30-30 case down to 7 mm (.284 in). read more