The older Tanaka models did have a problem with breaking, one major problem was the rounds they used as the construction made them too powerful for the plastic and parts would break. In recent yrs Tanaka changed the rounds to evolution rounds so still work as well but dont produce the pressure the old rounds did so a lot gentle on the guns. Tanaka also strengthened parts of the guns themselves so between this and new round design breakages are less likely to happen.
Just make sure you by the evolution models or the evolution HW models all work well and are unlikely to break, however you cannot rule out breakages on this guns as they are plastic at the end of the day but the new models are pretty good.