[jmr40]

Solid copper bullets don't play by the same rules as conventional bullets. Within certain parameters more velocity and less weight is a good thing.

Those bullets usually retain 100%, or very near 100% of their weight at impact regardless of impact speed. As long as you are using a bullet with enough mass to reach the vitals of the animal you are shooting then they are good to go.

And it takes much less weight than you think. For years we have used heavier bullets than really needed because we knew that a lot of weight would be lost at impact and the extra weight was needed to ensure penetration. Conventional bullets will lose at least 20% and as much as 80% of their weight at impact with around 50% being the norm. A 180 gr 30 caliber bullet will actually weigh somewhere between 90 to 140 gr after impact. A solid copper bullet that starts at 90-140 gr will still weigh 90-140 gr after impact and give comparable penetration.

But like everything else there are downsides. These bullets need to impact at speeds of 2000-2200 fps or they don't expand at all. While an 85 gr bullet at 3800 fps looks good up close it will also drop below the 2200 fps impact velocity at closer ranges than a heavier bullet that starts slower. It will also be pushed around by the wind a lot more.

Plus a conventional bullet will still expand with impact speeds in the 1600-1800 fps range. Considering that they retain speeds better, and they need less speed to work, conventional bullets are still the better option once you start getting to moderate to long ranges. Where the solid copper bullets shine is that they allow small caliber rifles to be very close in performance to larger calibers at closer ranges.