1 1/2 in is the ideal length but you still go through veins since you start at the surface and yes you can still hit a vein that deep, that is why you aspirate.
29g is really VERY thin and would not take much to break it off. I use 25g myself, 21g to draw because I am in NO hurry when it comes to injecting and taking 2 minutes is no big deal especially since it saves 2 days worth of soreness since most people like to
inject FAST and cause bruising of the muscle due to BLASTING the fluids into the muscle.
