Good morning Steve,
I have been using my .303 British, Ruger #1 for whitetails since 2010.
My favorite bullet is the Hornady 174 grain round nose. These are readily available and inexpensive.
I have had complete pass throughs from all angles regardless of the size of bones that were hit.
In testing these bullets expand well, hold together and retain 80%+ weight.
Most deer drop within 20 yards.
I picked up some of the Remington 180 grain Corelocks but have not shot any yet.
Sierrra 180’s are designed to expand at velocities higher than the 303 can produce so I have not tried these.
150 grain Hornady bullets also work for deer but the meat damage is greater and are not as accurate as their 174’s so I do not use them for large game any more.