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Old March 10, 2013, 10:58 PM   #17
Rainbow Demon
Senior Member
Join Date: September 27, 2012
Posts: 397
The Springfield 1903 was originally intended for use with 220 gr round nose bullets ( the .30 of 1903), and they settled on a 1:10" twist rate for that long heavy bullet. The same rate of twist is commonly used for .30-06 rifles.
While still very accurate when the lighter 150 ball and 175 M1 or match grade grain bullets are used, the 1:10 twist was not optimal for that weight range.

The .308/7.62 NATO rifles commonly use twist rates of 1:12"-1:14", better suited for bullets of 175 gr or less.

I suspect that all other factors being equal the .30-06 rifle would outshoot the .308/7.62 when the heavier 220 gr boatail matchgrade bullets are used. You don't see bullets heavier than 175 gr used very often in long range match shooting, because its hard enough to maintain super sonic velocities to or past 1,000 yards with bullets of that weight range, loading the 220 gr to such velocities would require a magnum case to maintain safe chamber pressures.

One might build a .30-06 rifle on a 1:12-1:14 twist barrel and find out for sure just how well it stacks up when 150-175 gr bullets are used at the max velocity available with the longer case.

Much match shooting with the .30-06 during the 1960's was done using the 168 gr AP bullets. A very good and highly accurate bullet, but not designed as a matchgrade bullet, and with 2-5 grs variation in weight from the factory specs.

As for use with a can, the .308 case with heaviest bullet available would be more efficient when loading for sub sonic velocity. Maybe not as accurate as it would be with a tighter twist though.

Last edited by Rainbow Demon; March 10, 2013 at 11:06 PM.
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