Day of the Jackal
 

In the original movie can anyone here tell what caliber the weapon Edward Fox (Jackal) used?

thanks

The caliber was never described in the movie, although the bullets that are shown appear to be either .22 Magnum or .22 Hornet cartridges.

The book doesn't say either, just somewhere between .22 and .300 Remington.
The 'explosive' rounds (I don't think they're described in the movie) have a hollow partially filled with mercury. On impact, the mercury's inertia hitting the front of the hollow is supposed to split open/fragment the bullet inside the target. I've never heard of that before, but it sounds like it should work. Maybe.

After reviewing the movie about a dozen times I figured it out. Its a 22 mag.