they do it in the movies but i don't think it will work in real life.

Why, when you get 22lr ballistics?

And maybe they're using 22lr in the movies?

Yes but it will not cycle

There are some youtube videos on it.

The author I watched didn't go into reloading details... powder used and grains ect...

The velocity was in the 1050 to 1100 fps range.

It's been done in the past and made to cycle, but way more work than just a mag change (like 300blk).
Short gas system, fast twist, heavy ~100gr bullets.

Now you can buy this stuff, but there's zero draw for me when 300blk subs exist at less than half the cost and twice the energy.

https://www.midwayusa.com/product/1019570122

Open up the gas port to improve cycling of the action.

I have a 8.5" 300blk with a 0.125" gas port that allows for 110gr bullets to cycle the action at well below sub velocities.

Did some loads just to see how low of charge with W296 would cycle the action consistently. 12.5gr cycled around 90% of the time. I didn't use a chrony at the time to get actual velocities, but the crack went away somewhere around 14gr IIRC. I want to try something similar again using another powder. Low power loads with H110/W296 is not recommended by the power manufacturer. The recoil was like shooting a bb gun.

I'm sure you could open the GP and adjust loads to work with 223 without too much trouble.