Never hunted the area but have hiked it a bunch. Certainly in September, but even in October and November, I would expect this to be a high traffic area with recreational dayhikers and backcountry enthusiasts. Quandry is one of the easiest 14er's and thus attracts bunches of crowds. Most of the hikers will remain close to the trail along the Eastern ridgeline that leads to the summit, but there are still plenty of others who walk the road into McCullough gulch.
Could still be reasonable hunting, but don't expect to be alone.
Rather than spend my hard earned pennies on those cool Shoot-N-See targets or even the preprinted targets at sporting goods stores, I save a few bucks for weekend plinking sessions by using paper plates as targets. A 100 count pack of paper plates costs less than a 10 count pack of preprinted targets.
If you are playing with something like a semi auto AK, or building a young shooters confidence with a 22 or shotgun, those big eight inch blanks are perfect for putting holes in all...