I usually use a 21g but have used 18s before. I've had no problem drawing the T with them- I've never done the needle transfer thing.
One funny story. One day I got a 23g and when I injected it didn't even break the skin- the needle just bent! Now, I have no buns of steel- that's for sure- so I have no idea what happened. Since my first 23g trial failed I just use 21s now. I can't even imagine using a 25g.
