I bought a 7.5 inch dedicated .22 cal barrel from Beyerbarrels.com last year, (terrific barrel, the guy is great to deal with), and built a vanilla upper on a Spikes lower.

I was/am really happy with it, suppressed.
Comes with a dedicated collar that fits into the Spikes .22 cal bolt I've had forever.  I also bought a CMMG Atchisson bolt on sale last year, the dedicated Beyer collar fits that as well.

Anyway, I've built several sidecharger 9mm uppers, and I really like them, the Matrix was the best upper I've used.
But I kept looking at the 9mm ejection port and wondering if it'd work with a .22.

So I found a great deal on the EE for a 9mm Matrix upper, bought it, and moved the Beyer barrel and Atchisson bolt to the 9mm Matrix upper.

Just stating anecdotally that it works well enough for me, and I'm super happy with the build in this config.

The Atchisson bolts don't travel too far back inside the Atchisson frame, and rearward travel puts the face of the bolt just slightly behind the rear of the ejection port.
It looks like the brass slightly pings the rear of the port, putting the brass between 1 and 2 o'clock about 6 feet from where I'm standing, but thats fine with me.

Anyway, I haven't seen anyone talk about this config yet, so I just figured I'd put a datapoint in the forum.

Pics so I can copy your build.

OST

Just as an FYI the NFA/Gibbz Side chargers have larger openings from the factory. The Matrix one is significantly shorter Left to Right. I had to mill mine out to work reliably with various 9mm ammo. So if you're having issues clearing the port, you can either mill/file/dremel or.... use an NFA/Gibbz/Spartan upper instead.