Superposed load question

Are any companies trying to create superposed load weapons that can actually be used in combat?

I didn't even know the term "superposed load" until a few minutes ago. I'm not a gun guy but I ended up on the Wikipedia page for Metal Storm which went bankrupt in 2012.

Metal Storm
Metal Storm Limited was a research and development company based in Brisbane, Australia, that specialized in electronically initiated superposed load weapons technology and owned the proprietary rights to the electronic ballistics technology invented by J. Mike O'Dwyer. The Metal Storm name applied to both the company and technology. The company had been placed into voluntary administration by 2012.
[...]
Metal Storm used the concept of superposed load; multiple projectiles loaded nose to tail in a single gun barrel with propellant packed between them. The Roman candle, a traditional firework design, employs the same basic concept...

I didn't understand so I watched this video...

The Weapon That Can Shred Any Tank to Pieces
The Metal Storm gun, a design with 36 barrels, has an impressive rate of fire of over 1.62 million rounds per minute, equaling 180 rounds in a .01-second burst. It employs caseless 9-millimeter ammunition that can fire a wall of 24,000 rounds that move at speeds of Mach 5. And it can literally tear apart any tank that stands in its way!

Skip the historical intro and go straight to the stuff about Metal Storm.

What the video mentions...

"The gun was stacked and couldn't be moved."
In theory a Metal Storm gun could shred a tank but in reality it's nonsense. See #1.
"The time to prepare it was tediously slow." I don't understand why the vid didn't use the term "reload".
"It was never produced to [fire for more than five seconds.]"
The gun/ammo was very expensive.

I'm not surprised the company went bankrupt.