[nordsieck]

> It would still serve to slow the projectile faster than it would be without

That's not even clear.

One of the common problems for bullet manufacturers with the "FBI protocol" suite of tests used to be the "heavy clothing" test. Shooting through several layers of denim would clog the cavity of the hollow point bullets and cause them to over penetrate.

Simply put, it's extremely difficult to predict how bullets will react to barriers of any kind in lieu of testing.