who make a good one? I have a extra upper wo a bcg I might as well make it a 22lr.

The Lower makes no differance
CMMG SS bolt
22LR dedicated barrel
Redi-mag adaptor and use S&W M&P 15-22 mags

The lower has a auto sear. Make lots of difference.

That makes more sense
I live in different world where those are not allowed
Sorry

Same above, just add the cmmg autosear trip, I've got an RLL so nothing works for me unfortunately, but the stainless cmmg kits I've had the best luck with in semiauto, and the forward assist comes in handy. I'd just get the drop in kit and skip the dedicated barrel, I've not noticed a whole lot of different between my dedicated barrel and the drop in shooting bulk pack ammo. S&w mags rule. For 22 full auto I've got a lage kit for my m11/9 and get good results from Remington golden bullet, and anything cci of course.

https://www.cmmginc.com/shop/auto-sear-trip-kit-22arc/

Amy concern with .22 uppers about them egging holes, like 9mm?

Not at all, they can barely reset the hammer.

It's not just a sear trip, you'll need an anti bounce weight as well.  The CMMG kits work great.  The red mag sw adapter is a must, as suggested above.

Some users have found that they have to install a light hammer spring for reliable .22 operation - I'm guessing that it may be ammo dependent.  Similarly, some users have found the anti-bounce weight unnecessary; that said, I don't know if CMMG sells the trip and weight separately.

Best of luck with your project, and with finding low cost .22 ammo.