What would be the penalties if the us ( and presumably nato at some point ) were to decide to adopt a more powerful cartridge like the 6 . 8 mm remington spc or 6 . 5 mm grendel 如果美国（以及此后某个时间的北约）决定换装诸如6 . 8毫米的雷明顿spc或是6 . 5毫米格伦德尔弹药筒等更强劲的弹药时会有什么负面效果呢？
The 6 . 8 mm remington spc is limited to relatively short bullets to fit within the maximum cartridge length of 5 . 56 mm weapons , so the grendel has a shorter ( 39 mm ) and fatter case , leaving room for longer , low - drag bullets , which retain their velocity out to long ranges 8毫米的雷明顿spc缺少相配套的短弹头使之合适于5 . 56毫米武器的最大弹药筒尺寸，因此格伦德尔的弹壳更短（ 39毫米）更胖一点，为远距离低阻弹头留出空间。
