It seems clear that there are two schools of thought here:
(1) What difference does it make in the long term?
(2) I'd rather conserve my brood stock for better weather conditions so when the rains return my flock will recover faster.
Mike obviously follows the latter principle. The best two suggestions so far are forego the covey shot and chase singles, and alternatively to reverse roles with your shooting student and learn to shoot badly...Geo
I would say:
1)I agree with Ted that what I do doesn't make any difference in the long run in the total world population of bobwhites.
2)I believe what I do this season on my lease can and often does make a significant difference in that lease's next season's crop of birds.
Ted and I just disagree on the time that Nature takes to fill that abhorrible vacuum I create on my lease when I kill too many birds or shoot out a covey.
Ted never quoted a time frame for which this would happen. But, I did point out the all too obvious (something I'm really good at) actual problem, which is the fact that most of the good quail habitat has become far less so. Including, your's.
I also suggested you read a book by an author who tried to make his farm into quail shangri-la, and when it was all over, came to different conclusions on how/why or even if, that is possible.
You can attempt to stack the deck, in the quail's favor, but, in the end nature can be a cruel minx.
Good luck, at any rate, and in the end, it will matter very little to nothing what gun or ammunition you shoot.
Best,
Ted