Prashantji, I'm pretty sure the movie you refer to is the old "The Day of the Jackal," the same one I'm referring to above. However, that scene was correct, in that the Jackal shot the melon with an exploding bullet. He not only wanted to test the gun (in the movie), but also the exploding bullet he was going to use for the assassination.Remember someone (I think it was XL) post a video (sometime back) from a Hollywood movie where this fellow shoots a pumpkin (or something) with a rifle and the thing blows into pieces.
The movie is actually a very good movie - one of my favorites. The Jackal sights in his rifle with regular rounds by shooting at a melon hanging from a tree limb, and then fires an explosive bullet at the melon, causing it to explode.
This site has a writeup on the rifle here:
http://www.imfdb.org/wiki/%22Day_of_the ... iper_Rifle
and on the whole movie here:
http://www.imfdb.org/wiki/Day_of_the_Jackal,_The
As can be seen, this site is quite a resource when it comes to searching for guns used in movies.