What some of you don't realize is that the 100% copper bullets are very long for their weight. The 155 Barnes TAC-XP is longer than a Hornady 200 XTP, thus the bullet occupies powder space and will raise chamber pressures. Finding a balance of velocity/performance versus pressure will be paramount!
Also over driving any HP design can roll back the expansion past it maximum and shed petals or become a smaller diameter too guickly.
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