WASHINGTON (UPI) — The DuPont Co. has agreed to stop selling teflon to the producers of the KTW bullet, which will pass through bulletproof jackets, a con gressman says. Rep. Mario Biaggi, D-N.Y., a former New York po liceman, is trying to outlaw armor-piercing handgun bullets such as the KTW, which uses a Teflon coating as a lubricant that allows it to glide through the equivalent of four bulletproof vests. Biaggi said the Teflon — used as a non- -stick surface on frying pans — increases the bullet's penetrating power by about 20 percent.