6.5 PRC vs .300 PRC
A to-scale size comparison of the 6.5 PRC and the .300 PRC, drawn from SAAMI and C.I.P. cartridge dimensions and aligned at the case head.
6.5 PRC (left) beside .300 PRC (right), shown at the same scale.
The 6.5 PRC has an overall length of about 2.96″ with a 0.264″ bullet. The .300 PRC runs about 3.70″ on a 0.308″ bullet. That makes the .300 PRC about 1.3x the overall length of the 6.5 PRC. See the full reference for each: 6.5 PRC and .300 PRC.