I am guessing you are firing .22 rimfire?, some helpful hints might be,follow through with each shot and dont rush them, pay attention to wind flags as there is far more space between muzzle and target for the bullet to be affected, pay attention to whoever is taking you as they will have very good pointers which will be relevant on the day, ammo quality hence price is more relevant at longer smallbore ranges ( I use Eley Team or Match and get reasonable results), I aren't sure if its because of the lack of movement in the horizontal plane but I find shooting at 100 yards far easier than I do for 25 or 50 yards,with the weather as we have had the past few days you might also experience the effects of haze(mirage) obscuring your target when scoping your shot holes and also affecting the target picture whilst aiming,
I hope this is of some help to you and you have a great day
ATB Martini
Sorry rto welcome you to BBS I just noticed it was your first thread