I am a believer in the copper bullet for hunting with high velocity cartridges such as the .243 Winchester with 90 grain E-Tips. The E is for Expanding! It is as accurate as all get-out!
Mushroom at 20 yards 1/2 inch mushroom below.
Weight before: 90 grains
Weight after: 89.9 grains
Weight retention: 99.9%
For contrast there is a 100 grain Speer Hot core boat tail lead bullet with gilding copper jacket shot at left of the all copper e-tip. The lead bullet exited the wood but was not recovered.