does anyone make these? 1/2 - 28? Or is there someone who can make them? I've come to feel this cz 99 would make an excellent host pistol for my ti-rant.

since this clone is similar to the sig P-228  you might want to ask a friend with a P-228 or 229 in 9mm if you can compare the barrels, if the barrels are close you maybe abole to handift a aftermarket sig barrel to your  cz99, if the barrel is like the walther P-88  then ask for dimensions on the wather sites  maybe able to do the same.  that the problem with these pistols   think on these lines when you need  parts for these istols

Unless your CZ999 is not the compact which would require the length of a P226 barrel instead

I own two CZ 99 pistols as well as a HS 2000 - the Croatian pistol that became the XD9.

It is very apparent to me that the barrel design of the HS2000/XD9 was copied from the CZ 99 (neighboring countries).

I'd bought an AAC threaded barrel for the XD9 - I found it will amost drop in to the CZ 99.

XD9 4" barrel is too short, but a 5" XD9 barrel may - with some small modification - may work in the CZ 99.

I plan to get a longer XD9 barrel at one point to experiment, but too many projects are ahead of that one.