Well, I think I am wasting my time posting here, since a guy that can shoot ½" groups at 150 yards is so full of sh** that his eyes are brown.
As a matter of fact, ½" groups at 100 are plenty tough to attain with anything but the best rifles, best ammo and zero wind.
Nevertheless, some very fine groups are possible with the lowly 22LR
I have a Suhl 150 set up by Jim Williams for benchrest, and a 40X Remington that also shoot "lights out"
These shoot regularly under ¼" at 50 and ½ to 5/8" at 100
I have even shot a few groups at 200 that are under 1" [5-shot groups]
I'll post a couple and you can judge for yourselves.
Suhl @ 50M 10-shot groups, shot on a very calm morning. [Eley match EPS]
40X @ 50M also shot on a very calm day. [Eley match EPS]
Remington 541T @ 50M some slight wind, but generally calm [Lapua Superclub]
Here is a couple of 5-shot 200M groups from the 40X on a dead calm day [Eley EPS]
My 452 American is a 3/8 to 1/2" rifle at 50 consistently with good ammo [RWS Rifle Match]
I also have a 541S and a Winchester 52 Sporter that will shoot nice small groups with ammo they like.
I have never seen ordinary run-of-the-mill ammo shoot consistent groups from any rifle, so am very sceptical about claims that say so.
Regards, Eagleye.