Back in the day, I fired an M14 for qualification, using a tight sling. One string I recall well was sitting position at 200 yards. We had 50 seconds from standing to drop into sitting position, check our body alignment, when set fire 5 shots, change magazines, fire five more, clear the rifle. In proper position the shooters offside bicep rested on his shin and his body was wrapped around and to the rifle. When relaxed, not using muscles to push the rifle one way or another, the shooter should be able to look through his sights and see the front post resting on the target. On this day when I sat into position, closed my eyes, took a breath, opened, looked through the sights, I was off target; so I squirmed around to get my alignment on target. I moved my body relative to the ground, not the rifle relative to my body. closed, breathed, opened; wrong place again. Seconds ticked off, shooters around me firing away, I had yet to fire a round. Squirm around some more. Close, breath, open. Ah ha!! Front post in the bottom of the black of the D target. Fire away, The rifle recoiled back and straight up. My body rocked back forward, dropping the barrel straight down through the target, In the black, fire, recoil, recover repeat, change magazine, close eyes breath, look- in the black, fire, repeat. To my surprise the targets didn't drop down leaving me with a bunch of saved rounds, to the contrary, I fired all ten, then sat there for at least 15 seconds before the 50 seconds elapsed. I recall my trigger squeeze being a little slow on one occasion, which resulted in a low hit, just below the 5 ring, but the remainder were in the 5 ring and a nice pattern of about 4" in diameter. Since it took 10-15 seconds to get situated, and I had about 15 seconds remaining, another 5 seconds for magazine change and recheck- that means I fired 10 shots in the span of 15-20 seconds placing 9 in the bull, 1 just out. That score was possible because I used no muscles to keep the rifle aimed and my alignment was such that at rest, the rifle pointed at the target and the hold was such that the rifle recoiled straight back and slightly up each time, sliding back down to the pre-fire position.
I the hold of the rifle allows for the rifle move differently during recoil from shot to shot the barrel will be pointed in a slightly different direction as the bullet leaves the muzzle, which will result in less than desired groups. Practice at keeping the various things into which the rifle recoils the same and you will see your groups shrink.