If it was a 20, I wouldn't touch the stuff. I only use Turkish Shering Primo's so can only comment on them. I use a 23g, but it's pretty tough thru a 23g, you need to warm it up under running warm water to really get it thru with ease.....Shering uses very thick oil, I've tried 25g before, and NO WAY, wouldnt come out.
what does 23g minimum mean??? Do you mean 23g maximum???? Because if something will come out of a 23g, then it will obviously come out of something thats larger like a 22 or 21 or 20 or On and ON!!!!!
(You did know that larger the number the smaller the pin---I am assuming that you as a 1/2" 29g Slin is extremely small and NOT the NAIL that a 20g etc is)........
(homebrewed Schering Primo's---you must be rather good bro)