I already thought of this and came to the conclusion its a very very bad idea. This bullet soley relies on aerodynamics and spin for stability. If I introduce anything to the streamlined shape it could tumble even if I get the rifling twist rate right. Then I thought of making a groove on the bullet itself for the tape to rest in but then it would be almost impossible to extract it from the mold in one piece since I have to push the bullet forward.
btw. if you havent tried already, tape doesnt stick to plaster at all, it just falls off
I've been thinking how the paper cone expands when you fire it and adapts to the contours of the barrel. I wish I could somehow adapt the same thing to solve the sealing issue.
First I thought of inserting a paper cone in the back of the bullet while the plaster is still watery to give it a better seal but quickly realized that the .408 bullet has a slightly tapered end to "calm" the airflow at the back making it more stable.
Any ideas? And no I'm not putting anything behind the bullet to push it like a tight fitting cork...