The main situation I am sensitive to unburned granules left over, is when shooting revolvers.
(I am not much of a pistolero.)
When they get under the extraction star, that can bind up the whole gun.
Normally a minor annoyance, this can get to be a true bummer in any kind of contest.
(looking at you Unique)
As I have said above, 4227 is one of my all time faves, but I don't use it in rounds below magnum pressure.
One thing that has always made handloading interesting to me is the fact that many shotgun or pistol powders
can be made to work in the straight revolver cartridges if one keeps one's head screwed on straight.
I enjoy making a combination possibly no one else has tried work successfully.
(Or prove it's not gonna work and let folks know that too.)