Are we sure that simply shortening the choke will cause it to produce a more open choke?

Not arguing here you understand, but I was considering opening up a 410 I have with a straight reamer, but then I got to thinking that the angle of constriction of the shot column would not be changed, just the diameter of the muzzle.

So my question is, are all chokes reamed with a reamer that has the same angle ground onto it? Meaning that one just reams deeper for a more open choke?

RedHawk