It's an interesting thought experiment but tough to break out into simple, even theoretical terms. Presuming the OP's question refers to interior ballistics (vice exterior), there really isn't an "all other variables being equal" scenario. The pressure-time curve is a function of a lot of variables, many of which are functions of one another including case capacity versus bore volume, bearing surface, and powder relative burn rate. You can't change just one without changing the others.
Unfortunately, there really isn't a simple answer.
Unfortunately, there really isn't a simple answer.
