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Rifles, Reloading, Optics, Equipment
Reloading
300 Win Mag Build and Loading Questions.
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<blockquote data-quote="Bart B" data-source="post: 1147582" data-attributes="member: 5302"><p>I've worn out four 30-338 Win Mag 1:12 twist barrels shooting 190 and 200 grain match bullets leaving about 100 fps slower than a 300 Win Mag would shoot them. All tested 15 to 20 shots under 5 to 6 inches at 1000 yards. Two were Obermeyer and two from Kreiger. That twist was also popular for 308 Norma Mags in long range matches. </p><p></p><p>Had one Obermeyer 26" 300 Win Mag hunting rifle barrel with a 1:13 twist and .307" groove that shot Sierra 180's into 10" at 1000 yards. Not bad at all for a 9 pound scoped rifle. </p><p></p><p>Boots Obermeyer along with Jack Kreiger are correct in using 1:12 twists for these cartridges. People laughed at the USN Rifle Team members shooting Sierra 190 HPMK bullets from 1:12 twist 7.62 NATO Garands in long range matches but shut up when that combo won. Famous barrel maker Harry Pope put 1:12 twist .30-06 barrels in the US Palma Team's M1903 rifles because he knew a 1:10 was too fast for best accuracy. Win 70 target models in 308 with 1:12 twist barrels shot WW and WCC 190, 197 and 200 grain match bullets very accurate. </p><p></p><p>Frankfort Arsenal spec'd M14 barrels at a 1:12 twist because it was better for accuracy for the 30 caliber bullets up to 174 grains used leaving 100 fps slower than the 30-06 shot them. Therefore, it should be obvious that popular 30 caliber magnums shooting those same bullet weights faster could do well with that same twist. </p><p></p><p>Don't forget; 308's shooting 155 grain bullets out at 3000 fps get record setting results in Palma matches with 1:13 twist barrels.</p><p></p><p>If a 300 Win 1:12 twist barrel won't shoot bullets up to 220 grains sub MOA through 1000 yards, the twist rate ain't the problem. Some people can't handle the truth because they don't understand, nor are aware of, the details making it so. Whatever twist and velocity combination spins bullets at the right rpm range for best accuracy is correct. If 30 caliber 190's leaving 2600 fps from 308 Win 1:12 twist barrels are very accurate at long range, they'll do just fine leaving 3000 fps or more from a 30 caliber magnum 1:12 twist barrel. </p><p></p><p>Spin rate in rpm equals velocity in fps times 720 divided by twist in inches.</p></blockquote><p></p>
[QUOTE="Bart B, post: 1147582, member: 5302"] I've worn out four 30-338 Win Mag 1:12 twist barrels shooting 190 and 200 grain match bullets leaving about 100 fps slower than a 300 Win Mag would shoot them. All tested 15 to 20 shots under 5 to 6 inches at 1000 yards. Two were Obermeyer and two from Kreiger. That twist was also popular for 308 Norma Mags in long range matches. Had one Obermeyer 26" 300 Win Mag hunting rifle barrel with a 1:13 twist and .307" groove that shot Sierra 180's into 10" at 1000 yards. Not bad at all for a 9 pound scoped rifle. Boots Obermeyer along with Jack Kreiger are correct in using 1:12 twists for these cartridges. People laughed at the USN Rifle Team members shooting Sierra 190 HPMK bullets from 1:12 twist 7.62 NATO Garands in long range matches but shut up when that combo won. Famous barrel maker Harry Pope put 1:12 twist .30-06 barrels in the US Palma Team's M1903 rifles because he knew a 1:10 was too fast for best accuracy. Win 70 target models in 308 with 1:12 twist barrels shot WW and WCC 190, 197 and 200 grain match bullets very accurate. Frankfort Arsenal spec'd M14 barrels at a 1:12 twist because it was better for accuracy for the 30 caliber bullets up to 174 grains used leaving 100 fps slower than the 30-06 shot them. Therefore, it should be obvious that popular 30 caliber magnums shooting those same bullet weights faster could do well with that same twist. Don't forget; 308's shooting 155 grain bullets out at 3000 fps get record setting results in Palma matches with 1:13 twist barrels. If a 300 Win 1:12 twist barrel won't shoot bullets up to 220 grains sub MOA through 1000 yards, the twist rate ain't the problem. Some people can't handle the truth because they don't understand, nor are aware of, the details making it so. Whatever twist and velocity combination spins bullets at the right rpm range for best accuracy is correct. If 30 caliber 190's leaving 2600 fps from 308 Win 1:12 twist barrels are very accurate at long range, they'll do just fine leaving 3000 fps or more from a 30 caliber magnum 1:12 twist barrel. Spin rate in rpm equals velocity in fps times 720 divided by twist in inches. [/QUOTE]
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