Will Smith -- Goes Ballistic ... Training for 'Suicide Squad' (VIDEO)

Will Smith has career options if this little acting thing doesn't work out ... because this video of him training for "Suicide Squad" proves he can handle cold steel with the best of 'em.

Big Willie is obviously taking his role as gunsling super villain Deadshot very seriously ... because he hit up a tactical shooting range in Moorpark, CA this week for a full day of popping lead.

We're told Smith spent the day with Navy SEALs and Army Rangers handling serious steel -- a Glock 9mm handgun and an AR-15 competition rifle.

Our sources say Smith was a natural who progressed very quickly -- especially during long range practice with the AR-15.

BTW ... Scott Eastwood also stopped by recently for some 'Squad' training -- even though his role in the movie is still top secret.