In my experience the standard 1:12" twist in most factory rifles is too slow to stabilize some 32 grain and heavier bullets. For that reason I build my own rifles in .204 Ruger and .223 Remington using 1:9" or 1:8"twists in custom barrels from Pac-Nor, Hart and Shilen. The exception is one Shilen .204 Ruger 1:12" twist custom barrel on a Savage Precision Action. Also, I have found that most, if not all, lead free varmint bullets from Nosler, Hornady and Barnes are more accurate than lead core jacketed bullets.

Below are two experimental groups (10 Shots @ 100Yards) fired from an AR-15 straight pull bolt action equipped with a Hart 1:9" twist barrel with no gas port.

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Below is example of Berger lead core 50 grain (discontinued) bullet fired from Pac-Nor 1:8.5" twist polygonal rifled barrel on a Savage Target Action.

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My standard varmint load of the .204" Barnes 26 grain Varmint Grenade over 25.2 grains of Reloader 10X usually shoots around 4,100+ fps, between .25" and .5", in any barrel. I am currently waiting for a new Pac-Nor .204 Ruger polygonal rifled barrel in 1:11" twist for a Remington 700 action. Fortunately, Pac-Nor is back in operation.

The key is a faster twist.