After a tracer bullet penetrates an object the bullet trajectory looks very strange, the bullet flies very slow but the tracer still looks 'long and stretched' like it's flying very fast, this gives very weird visual effect, the appearance just looks buggy.
You especially witness this alot when somebody is shooting with the technicals machine gun through walls and stuff. Suggestion to fix this, why not remove the visible tracer after penetration? Or alternatively use a different small burning tracer model.