I do not believe the old school guys with false muzzle actually engraved rifling at loading. Ballistics said the old timers (Pope) did not rely on bullet bump up. I beg to differ.
If they did engrave rifling with a false muzzle, I really doubt you could push a bullet down the barrel with a ramrod. It would be like trying to slug your barrel with a hand held ramrod by itself.
Think about it, when you slug your barrel, you actually beat the slug down with a mallet or hammer.
Of course those guys upset, or, obturated, or 'bump up', the bullet, we know they did, it is just that at that time they may not really known, or written down just what was happening.
As far as I know, Elmer Keith was the first guy to write about obturation, or, 'bump up'.
And Elmer Keith came along a long time after Pope.