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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Need groove advise...3 or 6?
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<blockquote data-quote="Bart B" data-source="post: 802764" data-attributes="member: 5302"><p>Some years ago, "Greek" 3-groove rifle barrels used in .308 Win match rifles were pretty good. They shot Sierra 168's through 190 grain HPMK's very well. 200's and heavier not quite as good. Don't remember the man's name who made 'em but it was a Greek one. Nice guy, too, from folks I've talked with who bought them.</p><p></p><p>All of Sierra's match bullets have shot well in 4 and 5 groove barrels. Bullets lighter than 160 grains seem to shoot best in these twists. 6 groove barrels never shot the 155's quite as accurate as a 4 or 5 twist one, but with heavier bullets they won virtually all the matches and set virtually all the records with bolt guns.</p><p></p><p>So, I'd recommend a 4 or 5 groove barrel to handle the greatest weight range of 30 caliber bullets. 5 or 6 groove for bullets 160 grains or heavier. Barrel length is not an issue for selecting groove count.</p><p></p><p>Regarding bullets coming apart in flight, most common cause is the rifling's lands engraved them such that they weakened too much at the land/groove corners at bore diameter. This was the problem with a lot of 28 caliber bullets when the 7 Rem Mag first came out. Boots Obermeyer used a 5-groove radiused rifling that worked with such bullets spun so fast from the 7 Rem Mag's 1:9 twist barrel and high muzzle velocities that solved the problem. I think jackets are better these days.</p></blockquote><p></p>
[QUOTE="Bart B, post: 802764, member: 5302"] Some years ago, "Greek" 3-groove rifle barrels used in .308 Win match rifles were pretty good. They shot Sierra 168's through 190 grain HPMK's very well. 200's and heavier not quite as good. Don't remember the man's name who made 'em but it was a Greek one. Nice guy, too, from folks I've talked with who bought them. All of Sierra's match bullets have shot well in 4 and 5 groove barrels. Bullets lighter than 160 grains seem to shoot best in these twists. 6 groove barrels never shot the 155's quite as accurate as a 4 or 5 twist one, but with heavier bullets they won virtually all the matches and set virtually all the records with bolt guns. So, I'd recommend a 4 or 5 groove barrel to handle the greatest weight range of 30 caliber bullets. 5 or 6 groove for bullets 160 grains or heavier. Barrel length is not an issue for selecting groove count. Regarding bullets coming apart in flight, most common cause is the rifling's lands engraved them such that they weakened too much at the land/groove corners at bore diameter. This was the problem with a lot of 28 caliber bullets when the 7 Rem Mag first came out. Boots Obermeyer used a 5-groove radiused rifling that worked with such bullets spun so fast from the 7 Rem Mag's 1:9 twist barrel and high muzzle velocities that solved the problem. I think jackets are better these days. [/QUOTE]
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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Need groove advise...3 or 6?
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