What material can be rolled into a cylindrical shape around a slug and inserted into the hull?

Teflon wrap is commonly used in ballistic applications because of its unique properties, particularly its low friction coefficient and high resistance to wear and chemicals. When rolled into a cylindrical shape around a slug, Teflon wrap helps to improve the movement of the projectile within the hull, reducing drag and enhancing aerodynamic performance. Additionally, Teflon's heat resistance helps protect the projectile from thermal damage during firing, contributing to more reliable performance. The material's ability to withstand extreme conditions makes it suitable for this application in advanced ballistics.

In contrast, while PVC tape and aluminum foil may have adhesive and protective properties respectively, they do not offer the same level of performance or durability required in high-stress ballistic environments. A plastic sleeve could provide some degree of protection but might not match Teflon’s effectiveness in enhancing performance and reducing friction. Thus, Teflon wrap is the preferred choice in this scenario.