You say you love animals in one thread and to a degree in this one, yet you don't own an FAC. Despite this and the obvious lack of practice you went and shot live game and were given the chance at a croc that needs to be hit very well in exactly the right place to kill it cleanly. How far was the impala? Big rifle, buck fever, unrefined technique doesn't sit well with me as being sporting. From reading many books and magazines the shots tend to be longer than they would be taken in this country at deer.
My advice, if you are going to do it and post about it, be aware that you can make yourself look unjustified easily. Learn well, dont boast and be careful on challenging others so virillantly.
A wise man once said to me, dont dig holes for yourself that are deeper that your longest ladder, instead use it to climb your way to respect. Which ever way the steps are long and hard, it's easy to fall, and if your not carefull impossible to find someone to hold it steady.