A lot of them are identical, but not all. I think Top Brass used to make theirs a little heavier, but not much. Call Starline and ask about theirs? Usually +P is just on the headstamp so that cases thus loaded are not accidentally confused with and chambered in a gun that can't handle +P loads. In .45 ACP that is often dependent on the barrel. If you have an integral ramp barrel in a 1911, the chamber is fully supported and there is no problem. If you have a chamber that isn't fully supported you risk getting more "pregnant" cases coming out of it from loading to higher pressures.