On 9/3/21, with a CZ 457 MTR 22 LR target rifle, at 50 yards, GECO Semi Auto ammo at $2.30/50, 10 5-shot groups averaged .415”.
This set, plus the previous 11 sets of 10 groups with the same lot of ammo, averaged .462”.
That’s 12 sets X 10 groups = 120 groups X 5 shots/group = 600 shots
I never cleaned 22RF guns, for decades. After moving to FL, with high humidity outside and cool inside. I started cleaning.
I bought this rifle new, clean it and all 22RF with a 17/22 cal. pull through, 17 cal. nylon brush with a paper towel patch wrapped on, CLP on the patch. Clean every time it’s shot. 3-5 patches until the patch is clean. I never brush 22RF.
This rifle has fired 3392 shots.
BSA 12/15 and two BSA International MK II rifles, Ruger Charger, same cleaning story.
If there is a hideous carbon/lead buildup, carbon ring; then it doesn’t affect accuracy where I shoot, in the .4”-.5” 5-shot 50 yard vicinity, with cleaning as described.
The standard deviation of 22RF, 5-shot, 50 yard groups, over 4 rifles and 630 groups is .133”; the standard deviation of that standard deviation is .041”. The .041” suggests that the .133” is an accurate estimate.
This suggests that 100 yard 5-shot groups, CF or RF, have a standard deviation of ≈ .27”.
68% of 5-shot groups will be ± .27”. A 1” average gun etc. will shoot .73”-1.27” 68% of the time.
Over the past three years I have fired over 7000 22RF shots per year, benchrest. In the past year I have not noticed any improvement in my accuracy. Ammo? Gun? Rest? Yes. But I am not improving. I believe that after learning HOW to shoot, practice does not improve accuracy.