The danger about using high pressure ammunition is the cylinder bubling or actually exploding. Guns which are rated for +p have stronger or thicker metal in the cylinder. If you use ammo which is rated higher than the cylinder, and it can't handle it, the cylinder will actually explode, splitting the side sending hot gasses, flames, shrapnal, all that good stuff out the side, ruining the gun and your day. A friend of mine overloaded his black powder .44 and that happened, he didnt get hurt, luckily, but its an ugly revolver now! It doesnt seem like the difference between 38 regular and +p si extremely too much..., but I doubt it would be recommended by the manufacturer.