Home Forums Reloading Big Game Rifles B.C. and bullet construction question

Ok, first, just curious. I know it has no bearing on killing stuff. The question is, since trajectory is ruled by velocity and ballistic coefficient., and since B.C. goes up as bullets get longer, but velocity goes down as bullets get heavier, can't we make bullets out of something light, and get light weight but high B.C. bullets?<P>I'm sure someone, probably the military, has tried this, but I'm wondering what would happen if soft aluminum (or even hard) was made as a medium weight bullet (say 165g for magnum .308 cal.). It should have a very high B.C. The velocity would be higher. If construction was well done, i.e. barnes x type, the animals would not know it was made of aluminum (they can't tell x bullets are not lead...). For reference, copper is 79% specific gravity of lead, and aluminum is about 25%.<P>Any thoughts , stories, or experience?<BR>John

BC is acually based on the density to diameter, not lenght to diameter. To raise the BC of a given caliber you have to increase the weight. When you lighten a bullet or change to a lighter metal the bullet will acually shed velocity faster. The momentum of the heavier weight over a smaller area is what keeps it going. Lead is the heaviest metal that is practial for bullets at this time, although the military does use some exotic alloys in special purpose munitions.

Just for your information, there is a small commercial bullet maker making, I believe, tungsten bullets in .308, they would have an incredible BC, but he charges about $3 each for them. I think I will have to make do with something a little less exotic.

Ok, I don't have the definition of BC here, anyone have it? Why are barnes X bullets solid copper) so much higher BC than jacketed lead bullets?<P>John

As far as I know bc is simply "how slippery" the bullet is going through the air. Probably the only way to test it is to clock the speed at the muzzle with a chrono and then time it's impact down range. However little speed it lost will determine how "slippery" it has been. Just cause a bullet has a polimer tip doesn't necessarily mean it will have a great coeficient. Barnes x bullet doe have great coeficients because they are "long" for their weight which evidently lets them be more "slippery".<BR>BTW--I read an article a while back where a guy was testing a varmit bullet in a .308. It had some kind of polimer/high tech makeup which made it extremely light for it's length. If I remember the picture it weighed about 80 grains yet looked like about a 125 grain speer tnt. Supposedly the guy was pushing this bullet at about 3700-3800 out of his .308!! He never reported accuracy. I tried to find the company on the internet but couldn't find them==I think they were being made in pennsylvania or somewhere out east. The next few years, I believe, will show us some phenominal changes in the shooting industry. We are like every other sport out there--golf, bowling, you name it---we are willing to spend lots of money for new things and industrious people are dieing to take it!!!!

Hey guys, Had a major brain fart, I went off on SD not BC....DAAHHHH. What we`re looking for is the relationship between the bullets sectional density and its shape, weight to caliber plays a role but the coefficient of form is also a factor. I don`t remember the formula but the way I`m going I`d screw it up anyway, Sorry........Ol` Joe