The idea behind all those American rifles with the staples under the cheek - a good number w/ a feather quill there, old or newer - is that this was shoved in the vent prior to loading to keep it open, then withdrawn and pan primed. Functional, effective, works well with a fairly large honkin' straight drilled vent.
Nevertheless, an internal cone, regardless of how executed (liner or internal coning tool) is very definitely faster in daily practice.
I do think large brass, nickel, or whatever, liners look hideous on American guns, however. But, plain steel can be blended-in quite well.