I must admit I read the same thing somewhere and so was hopeing to hear more on the subject of bottleneck vs straightwall cases. It seems the arguement went: the equal and oposite force of breech thrust was against the base of the bullet in the case of the straightwall and against the case shoulder and the base of the bullet in perportion to their area. The duration of the breech thrust is then a function of the time needed to attain a specific volume relative to the smaller bore of the bottleneck cartrige. thus more (longer) duration, or was it all just a function of the level of Devils lake, I forget.