First effect would be to hear many of us here cry. Before you cut the barrels please sell the gun and find another for your needs. The chokes will be gone and it may not have the point of impact that you expect. On top of that it will become just one more short barrels that will never grow long again. If you want a short barrel double then buy one that started out that way instead of making one yourself. There is a real demand for a 16 with 30" barrels if you wish to sell the gun.