Shoot THAT rifle.

[Confederate rifleman]

We know how to shoot a rifle. But it's important to know how to shoot THAT particular rifle.
I learned this with a Marlin 336. That one would drop the first 2 shots on top of each other and land the 3rd about an inch and a quarter low and left. So I held high and right and shot some jaw dropping groups.
My ThunderHawk shoots well with the sandbag just ahead of the triggerguard. A solid 1 1/2 to 2 inch rifle at 100. But there were usually flyers that messed up the overall group, and group overlap could use some help.
So I tried moving the bag about mid forend and... Smallest group 1 5/16, largest 1 7/16 and all 10 were inside 2 1/4. Again at 100. The overlap of groups was excellent, and the 2 flyers were all me.
Sometimes it pay to fiddle around with rest positions etc, to see how THAT rifle likes it done.

 

[sabinajiles]

Good advice. Actually, the title of your thread says it all. Shoot that rifle. Shoot it a lot. I know many people that get a muzzleloader just to extend their hunting season. They buy prepackaged bullet/sabots and pellets. They go to the range to sight in the rifle, take enough shots to get it shooting 4-6" groups and are ready to go. Shortly before every hunting season they load the same load, take 5 or 6 shots to check the scope/sights and are ready to go again. I realize not everyone wants to shoot all the time or won't take the time and effort to shoot regularly but if you really want to get to know your rifle, and realize it's maximum potential, you need to shoot it on a regular basis, all year round. You need to try different bullet/sabot combinations and different powder loads in order to get the absolute best you can get from the rifle, not just be satisfied with "good enough". And if you really want to be accurate at longer ranges(>150 yd) you need to shoot a lot. As you said, accuracy, and shrinking groups, comes with knowing your rifle and knowing your rifle comes with shooting it as much as you can. I, personally, love to shoot and will put hundreds of rounds through my rifles before hunting season comes. I already know what my rifles will do and what loads shoot the best and the continual practice is to keep me sharp and in tune with them.