Phantom also have optional Detent rings that will prevent rollouts.
Carter made barrels with rubber widgets to prevent rollouts.
I personal love my Lapco .681 barrel and just under bore. I use a Lapco .681 on my Phantom, Bushmaster and my Carter Buzzard. All are stock class but I've never had a problem with double feeds and the accuracy rocks. I do break paint once in a while but thatís why I carry a squeegee.
To answer your question:
Yes, you can remove the detents and under bore to prevent roll-outs even with a hopper.