1. autocenter = 0 must be a named property. (alt-p, rmb, -'new', name: autocenter, value: 0)
2. make two identical models - really identical in terms of polgons, mapping etc. in the model to-be-unloaded select the rocket, go to vertex properties and enable 'hidden vertex', this way you hide the rocket but the focal point stays the same in both models, hence it won't bounce forth any more when fired