Ok,,,I was not going to reply, but this is a subject near a dear to my heart.
For the OP (6.8mmSPC_Fan), set up your gun, and go take some 2 or 4 day classes. Run some serious amount of ammo through the gun. Learn what your gun is doing. Find out what you can do.
I have 2 shotguns that I use for HD...
1. Original Bennelli M1 bought new in 1977, and competed IPSC 3 gun shoots with it for years. I shoot with the Armson Occluded Eye Gunsight (OEG).
2. Remington 870 Desert with a Vang comp barrel. with a Trijicon reflex sight.
Both will hold under 10" at 100 yards with the right slugs. Both will hold a 5" group with Federal LE 00 buckshot at 7 yards (don't be playing that peek-a-boo stuff with some hostage at that distance as you will loose), at 25 they open up to 2'.
I actively hunt each year, but mostly with 28 ga and 410's, but at over 70 do not compete any longer (too much emphasis on guns and impractical equipment for my taste). I try and take a 2 or 4 day pistol course each year, just to keep my eye/hand coordination up and 1 FOF class (either empty handed or edge weapon). So I am not your average over weight out of shape "wobbler"
To the point of all this and training....Last year just for the heck of it, I signed up for a 1 day shotgun class. This ought to chase the cobwebs out of the antique Bennelli, (that I had not fired a round through in 20 years. Found 500 rounds of BRI sabot slugs that I had stashed away over 20 years ago, bought a case of bird shot, and a case of Rio 00 buckshot, and 100 round of Federal LE 00 buck.
It was like dayshavoo all over again. The gun came up and the target fell down. At 25 yards the antique slugs printed at 2" with 3 out of 5 touching and 2 just below. The OEG sight was exactly where I had left it 20 or more years ago. Hot barrel and gun smoke, rapid reload, jam clear, it all came back.
Finally the big man on man shoot-off. 5 steel targets, single elimination. I really did not think I could or even should compete, but figured I could get by some of the beginners. Who do I draw on the 1 round, but a guy that takes this class every year. (And had the newest gee whiz gun and gear).
Competition is just a mini rehearsal for HD. You have an adversary, nervousness, and adrenalin, except you are not looking for cover, and are not being shot at. However you do have 20 students and several instructors judging your movements, and expertise, your every bobble. So as I come up to the firing line what do I do? Study your objective, know your moves, and envision the outcome you want. The end result, you need to focus on what you could have done better, and why you did not do that? Be your worst critic.
Well the whistle blew, and I picked up my 1st target fired, and kept moving for the next target, next target. Just as I squeezed my last target I heard the gunshot from my competitor, thinking I had lost....but as I was dropping my gun and watching the last target fall, there was another shot from my adversary. I had beat him by a full target. later that day I won the man on man.
In the end, there were a lot of comments about how did I learn to shoot so fast....The truth is I am not fast but was privileged to shoot with some of the very best in the world back in the late 70 early 80's. John Sacatterwhite, and Danny Reeves come to mind as 2 people that used to just humiliate me, and kid me back then when I was in my late 30' early 40's about being an "old man". Jeff Cooper at Gunsight, told me about the OEG sights, and mounted it on.
I will include my 12Ga training in my yearly exercises now, as I know how much faster I could have been, however until you train, and compete against the best, you will not have a clew about how good you can be. Or what fast is!!!
DO NOT JUST BUY A SHOTGUN, AND WAIT FOR THE NIGHT YOU BET YOUR LIFE THAT YOU CAN OPERATE IT WITHOUT FAULT, AND LIVE TO TELL ABOUT IT.
TRAIN TRAIN TRAIN.
Classes and man on man competition (even just a few friends and some clay pigeons set 3' apart is good fun. Taking ropes and hanging some plastic milk jugs full of water, then start them swinging, turn and fire against a timer will improve your skill level. We used to put up silhouette hostages just in front of the jugs to make it more interesting. ((Slugs or 00, how well do you know your pattern?)) ). These will show you your strengths and weaknesses. With a weakness, ask a person that you respect to take a look and make a few suggestions so you can improve. Do not keep practicing failure.