Just to weigh in on all of this experimentation and to set some minds at ease.
When you straighten out the last third of the case to the mouth, you aren't going to experience any real problems, one might associate with this process, Vis-à-vis, the extraction, after firing, process.
The example I can site is the 30 Carbine round. The factory fodder is in fact loaded in this fashion, e.g., the last half (not the last third) of that case is in fact "Straight". The reloading dies for that case however, resize the case for a total taper over the entire length of the case.
My personal 45 Professional dies, to this day include, a 45 Colt, 45 ACP, and 45-70 dies.
What I'm trying to say is, ..Don't be spooked by none-traditional loading practices. Your real questions should be, am I getting enough Bullet Pull, so I can burn the powder properly, or I might not care if the powder burn is efficient or not, especially if I can use a better bullet for my intended Mission (This might just be the biggest concern..can I kill the target? Can I retain enough terminal-ballistics, to decide the issue when the bullet gets to the target, be it paper, steel, or flesh). After you decide theses issues, the only thing left and this is Paramount, do I have the correct Head-Space and does the cartridge pass my Thunk Test??
Heck, I even Thunk Test Bottle Necked Cartridges. If you're not doing it then start. Imagine, spending 20 Grand on a hunt, you want to use your Home-Rolls and when you get Afield, you discover your cartridges wont chamber..Oops! From my PH days, I always thunk and then chamber every round I intend to use, for I have seen ruined hunts, over this little matter..
..t