I've heard that tracers are bad for barrels, but when I looked into it no one I asked really had firsthand info/experience on them. It looks like that info is out of date anyways.
One guy was pissed that his tracer bullets he bought didn't "light up" when he shot them at his local 25-50 m range, so he figured he needed special powder in his handloads to "light" the tracer compound. Hence the feeling that tracers are hard on barrels, plus when they light, the hot tracer element adds heat.
I found this all to be baloney... I handloaded some with "cooler" Win 748 ball powder and they lit up just fine. The tracers I shot weren't designed to light up until about 100 yds anyway. Supposedly because the military didn't want the shooters exact position to be exposed. So if they don't light until about 100 yds, theres no way they'd heat up your barrel....