Hey Buster, the Sherman tank was a piece of junk back when it was the best we had. The gun was useless against armor, it had thin armor, and it burned if you even looked at it funny.
The BAR, on the other hand, was the best thing one man could lug around. It would be entirely servicable today if it was belt-fed and weighed a few pounds less. Heck, it might be servicable without those mods...
I'm sure somebody is still using them somewhere in africa or the far-east.