I have a small frame 9mm witness, I just got a 22lr conversion kit.
it only comes with 1 mag, and it seems factory mags are unobtainium. which I should have checked before I bought, but oh well.
it seems you can still get the cz kadet mags. they are twice the price of the witness mags, but beggers can't be chosers. plus they make a metal version, not just poly.

since the cz75b mags work in the witness wouldn't the kadet mags work too? or am I missing something.
also anyone know the trick to getting the mag to lock back on empty? seems the mag spring is a bit weak at the top. I see it make contact, but doesn't push hard enough.

I have no idea about the witness. But in the kadet mags and cz75 frame sometimes you have to “weaken” the slide stop spring. By bending it slightly out of shape. Not too much because it’s also the slide stop retention spring and you’ll end up with phantom lock backs if you go to far when you go back to 9mm.

My solution was a dedicated SAO frame because of this but also the hammer spring. You need a full/extra power hammer spring to reliably detonate 22lr.  The lighter springs people use to improve the DA trigger in 9 are no go in 22lr.

Why did I spend nearly $1000 on a kadet kit plus dedicated frame?  And $60 a mag that are 10rds max with no high cap options?

Oh yeah… it’s stupid reliable and pretty dang accurate.

what i was tying to do was get a compact frame, and run sig p322 magazines in one.  that cut out on side of mag is an issue though...

yeah, the kit did come with another spring for just that I guess.
I also read someone replaced the magazine spring with a stiffer one but he lost 2 rounds.

for highcap mags, I actually was looking and beretta makes a 15 round 22lr mag for their conversion kits.
those also work in the taurus conversion kits and I checked my taurus mag and found it fit in the magwell of my witness.
but it wouldn't feed. round noses below the feed ramp for 9mm. but I really thought about buying one of the 22lr ones to cut and see if  I could make it work. but that will be my last resort if the cz75b mags don't function or I can't find any eaa ones.

well I got a set of metal ones and they lock in but won't feed.

the follower won't even come close to the slide lock either.
pity, they seem like nice mags.