Both the 165 and the 180 grain bullets in .30 caliber are .308 inches in diameter. Higher velocity means a 165 grain will usually expand more quickly than 180 grain of equivalent construction, creating a larger wound channel.
A 165 grain TSX will, a very high percentage of the time completely pass through small and medium sized animals up to 1000 pounds or more.
It has less recoil.
To rephrase an earlier question, why would anyone choose to use a 180 grain?
If 180 grains are better than a 165, then why not use a 200 or 220 grain?
