That was tested on Myth Busters.

Outcome was plausible.



During the Civil War, two soldiers’ bullets collided in midair and fused together.


plausible


The MythBusters first tried to mount two Civil War rifles in front of each other so that when fired, the bullets would collide in midair. However, this proved impossible because they were unable to get the guns to fire at the same time. Instead, they aimed a single rifle at a bullet suspended in the air. The fired bullet hit dead center, and the MythBusters found that both bullets had fused together into a single mass. Though incredibly unlikely, it is possible for two bullets to collide and fuse together in midair.