The numbers can have different meanings. 22-250 is a 22 caliber bullet in a 250 savage case. A 30-06 is a 30 caliber in a case designed in 1906. Or something like that. 25-06, 6.5-06 yada yada. Some are caliber x weight of black powder, like 45-70. The 7mm08 is a 308 necked down to 7mm.
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