Re: 30-06 vs. 7mm Rem Mag felt recoil
The only 7mm Mag I have is a Browning BAR and with full length sizing it gets head separations after a couple of reloads if I don't catch that the case is stretching. I now size the cases to allow the case to try to headspace on the shoulder or nearly so, to minimize the case stretching and the case head separations.
The belt is necessary IF the gun is set up (and the industry standards say it would be) to head space on the belt. If the belt were not there then and the chamber were done per the standard then the case might seat too far into the chamber and stop on the shoulder, making it hard to get the firing pin to get a good strike. Until the industry removes the belt and starts head spacing on the shoulder, the belt is necessary. The new cartridge and chamber would no longer be 7mm Mag but re-named something else.
The history of the belt comes along with much older cartridges that had very shallow shoulders or none at all and those shoulders were inadequate to hold the case in place when the firing pin hit the primer. Because rimed cases are hard to feed without the rims colliding in the magazine a rimless solution was thought necessary. Hence the belt on a rimless case. There also was a bit of advertising hype since the belt made a case look stronger as did the Magnum names.
A modern large capacity case does not need the belt and some don't have it. Those that don't have a belt have a pronounced shoulders for head spacing rather than the earlier design shallow angle shoulders used over a century ago.
Indeed the fix for reloader is easy as I explained earlier if you: know you need it and know how to adjust the sizing die to achieve it. So it is worth mentioning for reloaders. When adjusted for a shoulder head spacing, the case failure mode is burned through necks, eventually.