bought a 9mm colt leo lower ,no block came with it,can i use the block that uses uzi mags and a rock river upper?  thanks in advance!

most likely.

does it take a standard 5.56 M16 mag in the condition it's now in? If so, it'll fit any mag block, but if it has the the roll pin holes in the lower, the Colt/RRA style could conceivably cause problems by the "set plungers" lining up with a pin hole and not gripping properly. That's Highly unlikely, though, I'm guessing.

Can't speak of the Hy-Tech or others as I'm not familiar with them.

takes 223 mags now,is marked leo  9mm carbine

Does it have holes through the mag well area for roll pins?

I'm  positive you'd be fine with just a mag block from either RRA or Hy-Tech.

Worst case, you'd just have to pin it in with the existing pin holes, assuming they exist.  If not, you should be golden.

no holes for roll pins,made like a regular 556 lower,only marked 9mm.also thinking of useing a socom lower that takes sten mags and a olympic upper.

You can do whichever you like in that case.  You already seem to be aware that RRA and Olympic systems are different and require mag blocks compatible for each respective style.

Either way, you'll have fun. To me it'd be wrong to put an Oly system in a Colt, and vice versa, but I'm kind of anal that way.

What I would consider if I was you, is selling that lower,and getting another one, because somebody building a 9mm might pay a premium to have a 9mm marked lower.

How much for it?

id trade it for a colt leo marked 556 lower