The data I have supports Stagpanther.
I can only report the experience that I and 3 other range buddies who shot a total of 18 different .22LR target grade rifles using 57 different ammos over about 5 years. I hope this long post provides data that most people don’t have the opportunity or the time to gather.
We shot 5 round groups at 50 and 100 yards and the total groups scored was well over 10,200 groups.
We recorded everything so the amount of data we gathered is daunting.
The shooting sessions were all from benches using scopes, so barrel length didn’t aid in sighting.
Shooting sessions extended over multiple years, outdoors, under temperature conditions from 45 to 90+ degrees, and with wind conditions that varied but rarely exceeded 10-15 mph.
While there were some variations in shooter ability, especially in ‘reading the wind’ shooting at 100 yards, the large samples tended to balance that out.
Barrel lengths ranged from 18 to 26 inches.
Bullet velocity ratings ranged from 1,050 fps to 1,085 fps for match & target ammos and from 1,200 to 1,255 for high velocity ammos.
Our results show that the accuracy was more dependent on the rifle and quality of the ammo rather than on barrel length.
Unfortunately, not all barrel bores are the same, regardless of length, and the higher quality barrels tended to produce better performance.
At 100 yards, the quality of the ammo was the biggest factor.
Results:
2 Cooper rifles (24-in), a Winchester 52C (26-in), and 7 Kidd semi-autos (20-in) had the best performance at 50 yards.
2 Cooper rifles (24-in), a Winchester 52C (26-in) and 3 of the Kidd semi-autos (20-in) had the best performance at 100 yards.
At 100 yards, the rifles shooting the best overall averages tended to shoot more of the highest quality ammos.
Laupa X-act, Midas Plus, or Center-X, and Eley Tenex or Match, and RWS R-50 or R-100 generally had the smallest group averages at both 50 and 100 yards in most rifles.
Those 7 ammos generally had the best results at 100 yards regardless of rifle, or barrel length.
(Eley Team and Edge, SK Rifle Match, Wolf Match Target averaged just over 1.0 in at 100 yards and were not used as much, once it was found that the higher quality ammos performed so much better.)
At 50 yards, the best shooting rifles, in order, were:
2 different Cooper 57M rifles with 24-in barrels
Winchester 52C with a 26-in barrel
7 different Kidd semi-autos with 20-inch barrels
Sako Quad with a 22 in barrel
Kimber SVT with a 18-in barrel
CZ 455 with a 22-in barrel
3 Ruger 10-22s (modified) with 20-inch barrels
Ruger American
Remington 541X
The best group averages were achieved with high quality, match ammos.
At 50 yards:
The top 9 rifles shot under 0.5-in averages with all of the ammos.
7 of those 9 averages were between 0.404 to 0.444.
The top 9 rifles averaged under 0.4 inches with high quality match ammos.
5 other rifles shot under 0.6-in averages for all of the ammos.
1 of the 5 averaged 0.500-in.
2 rifles shot just over 0.6-in averages for all of the ammos.
Averages were 0.609 and 0.610.
The last two rifles averaged under 0.8 inches for all of the ammos.
At 100 yards only the top 13 rifles were shot using the moderate to high grade match ammos.
(Even with the most accurate rifles, tests of high velocity ammos showed that they couldn’t break 1.2-in
averages at 100 yards. Several could not even break 1-In at 50 yards.)
At 100 yards, the top 6 rifles averaged under 0.9-in for all ammos shot:
Ammo quality and wind conditions tended to be a major factor in getting consistent results.
0.724 Kidd with 20 in barrel
0.808 Kidd with 20 in barrel
0.836 Cooper 57M with 24-in barrel
0.859 Winchester 52 C with 26-in barrel
0.865 Cooper 57M with 24-in barrel
0.891 Kidd with 20-in barrel
At 100 yards, the best ammos in the top 6 rifles averaged:
0.649 Kidd with 20-in barrel (Lapua Midas Plus)
0.658 Cooper 57M with 24-in barrel (Lapua X-Act
0.732 Cooper 57M with 24-in barrel (Eley TENEX)
0.747 Kidd with 20-in barrel (Lapua X-Act)
0.789 Kidd with 20-in barrel (Lapua Midas Plus)
0.823 Winchester 52C with 26-in barrel (Lapua Midas Plus)