All of these in-depth comments are important as to handloading and shooter safety. I have a number of different weights of Hawk bullets in 348 WCF caliber.
The 348 case is a strong one, but the Winchester Model 71 and later versions are lever actions. Lever actions have no sense of humor and handle adverse pressure spikes poorly.
The factory warning is not to be taken lightly. That being said, it would help Hawk to close up the base of their bullets as much as possible, within their design
and jacket material. The older original Barnes bullets were made similarly. One could see where the copper tubibin was reduced at the base, leaving a very fine hole-
sometimes the core lead was visible.
This type of thread should be repeated regularly as a safety precaution-old school or not. Keep resurrecting................
