Anybody else have trouble with Atlas 40' box cars being to light? I have 3 CP box cars, all tend to derail easily, espically behing long locos. So I useall keep them apart and back a bit. Yesterday I pickup some lead weights and put a 1/4 oz square in. Huge differance, the cars the like to derail in corners didn't in fact I backed up in the corner with 10 hopper cars behind them!