Something very dichoctomous I missed here = "It has a repeat shot capability (pretty rapid) and if you shoot once and that's all you need, ....
HUH?
Likey your target is "under the umbrella" of the action noise anyway, & if you've smoked 'im anyway, what's the diff?
That's #1 = "all you need." Agreed, with stated conditions.
But, unless some ancillary persons = very likey, & still, if they're in the "envelope," they're not gonna hear the action cycling, & if so, a semi will be quicker (& "buried") better than a (slower - depending) pump, lever, anything manual action (other than a way quiet & purposeful bolt action - purely for steath. Still, anyone getting tagged will most likely make everyone else in the area take a bit of a "stay put" posture.
For all pratical purposes, any action's noise will be covered by the noise of the impact & action by 1) the impact (first) & then by the 2) report - if you synch it all. & yup, one shot is all that it should take, but at what range? Matters.
#2 is detection.
May be that at a distance that one could work a lever, bolt, whatever, but the thing is to remain totally undectected - forevermore = literally forever, & to escape the area & never have been there at all.
If "extras" in the area, they will hear your cycling unless buried in the report's noise.
Besides any actions you may take to cycle he action itself.
Minimal everything.