My experience is that there are better ways to flatten the curve

than a restriction at the port..I see it as a band aid fix.

Sometimes those "better ways" turn into a lot of work,involving valve head shapes and dimensions, lighter strikers with longer strokes,etc, but there are ways to get a valve to self reg so well that a separate regulator is not going to gain you much(if your preferred fill pressure is around 2700 psi)and part of that non reg'd flat string is good flow over a rang of pressures...much complicated by a strangled port.

Look at what Dave G has accomplished with his self built guns..long strings with tight spreads and no reg, from slim reservoirs.