Use a QB, an empty 12gr. with the neck drilled out so the piercing stem doesn't touch it, and a full 12gr. at the front end, the vel. should be the same as if i were to reverse that process (drilled empty to the front, new full 12gr. to the rear)?
Seems a simple enough test...its my week to be on call, and have been getting home a bit late for tests, but I'll get around to it.