#1). The answer is "yes."
#2). The explaination is simple. With rimless rounds where the unimproved headspace is on the shoulder that is cut away in "improving" the chamber there is a need for a support point for fire forming the cases in the new and improved chamber. Base of the neck??? Mr. A et al recommended turning the barrel back 1/4 turn (1 full turn if there were sights mounted so the sights would again be on top of the barrel -!!!) to assure a "tight fit" with this new and temporary headspace point. Mr. Gibbs just seated bullets "out" to "headspace" in the lands of the rifling for the .30 Gibbs on the '06 case. Sloppy. It can work. But Sloppy, per Mr. A.
b). The Hornet has a rim. It will headspace on the rim in all circumstances. You mess with the shoulder, no change, the headspace point remains the thickness of the rim. You are not changing the headspace at all. So this can be done with T/C single shots. Rimless, no, you should not. Some do... Understand all this, blow the shoulder forward a trifle, it can be made to work, but also dangerous to the uninformed and irresponsible... luck.
