Here is my thoughts about group Issues.
First, sit down with the rifle well supported front and back. Put the crosshairs on a dot target at least 100 yards away and dry fire. See where the rifle winds up after you squeeze the trigger.
Next, if you are satisfied, with your trigger pull, and follow through ask a fellow shooter to help.
Have the helper stand behind you and load your rifle with one round, or not with one round. Do this multiple times with no regular sequence so that you will never know if the fire arm has a round in the chamber when you squeeze the trigger. On the blank rounds, make sure the cross hair stay on the point of aim. Repeat until your rounds land at point of aim. If your scope is staying on the point of aim but your rounds are not hitting at point of aim, start checking mechanical issues with the rifle/scope/mounts/bedding and torque of action screws/bolts.
Now many may recognize that the above method is the way to help solve some one who flinches. You would be correct. However, getting a smooth, positive trigger squeeze, even when there is no flinch is not all that easy.
(this is where I get in trouble with the rest of the group)
As far as 3 shot, 5 shot, 10 shot, 5000 shot groups go. I say, this obviously sounds like a hunting rifle. As with all hunting rifles, the game animal normally is not going to wait on your barrel to cool so you can get a second aimed shot off with a nice cool barrel to assure that the bullet is going to go where its supposed too. Also, rarely is more than three shots are needed. Hunting is hunting. A quick follow up shot needs to hit exactly where the first shot went, which is point of aim. Rarely will a third shot be available but if it is needed it needs to Quick!
So, for hunting rifles, multiple three shot groups are much better than a ten shot group. Of course, following each three shot group it is then, important to let the barrel cool to ambient temperatures. The hunter needs to know where his bullet is going to go with a cold shot first round and follow up shots with a hot barrel. If they don’t all land at the same point of aim, there is a real problem with the rifle.
If this is a target rifle,
Rebarrel the thing and throw out all that I just wrote about groups.
Final thought, If a fellow needs to let his hunting rifles barrel cool down between each shot, consider the meme below.
Not the same thing but the same thought.