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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
.308 Project -seeking advice-
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<blockquote data-quote="trebark" data-source="post: 411426" data-attributes="member: 19172"><p>I think everything you have is compatible. Your gunsmith might have some personal issues with some of your items - but they always do. If a smith has a bad experience with an item or company, they will often prefer not to work with it again.</p><p> </p><p></p><p> </p><p>#1 - take a look at a loaded 308 cartridge and imagine it in the chamber of your rifle. This pic might explain better. Notice that the lighter bullet has more space in front of it before it reaches the lands and grooves of the barrel, whereas the heavier bullet actually touches the lands and grooves. Also notice that the base of ALL the bullets is in the same place. By having a lot of freebore, you are able to seat the heavy bullets farther out of the so they do not take up much case space. The advantage to a lot of freebore is that you are able to seat the bullets farther out and not take up any more case capacity than a lighter bullet. The downside of a lot of freebore is that if you want to shoot the lighter bullets, they will have a lot of 'jump' before the bullets engages the lands/grooves of the barrel (this can negatively effect accuracy). Given that in 308, bullets range from 155 to 210 grains, it would probably be good to throat your barrel for a 168grain bullet since it's about in the middle and a very common bullet weight for the 308. Make sense?</p><p> </p><p><img src="http://i342.photobucket.com/albums/o436/mtgrizzard/freeborenn8.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p><p> </p><p></p><p> </p><p>Imagine a quarterback throwing a football. Notice that when he throws the ball short distances, the ball does not (nor does it need to) rotate very fast in order to remain stable until the receiver catches the ball. Then imagine a 60 pass where the QB really heaves the ball down the field. Notice how the ball rotates very fast - in order to keep it in stable flight all the way to the receiver. Barrels and bullets work the same way. In order to keep a heavy bullet stable for long distances, it needs to be spinning faster than a lighter bullet. If you're building an all-around rifle in 308, you will want a rate of twist the is fast enough for heavy bullets, yet not so fast that it doesn't over spin the lighter bullets. A good compromise for the 308 is 1:11. Make sense?</p><p> </p><p></p><p> </p><p>No worries - always glad to help. It wasn't long ago that I was in your situation and counted on help from this site in order to learn.</p><p> </p><p>Keep the questions coming.</p></blockquote><p></p>
[QUOTE="trebark, post: 411426, member: 19172"] I think everything you have is compatible. Your gunsmith might have some personal issues with some of your items - but they always do. If a smith has a bad experience with an item or company, they will often prefer not to work with it again. #1 - take a look at a loaded 308 cartridge and imagine it in the chamber of your rifle. This pic might explain better. Notice that the lighter bullet has more space in front of it before it reaches the lands and grooves of the barrel, whereas the heavier bullet actually touches the lands and grooves. Also notice that the base of ALL the bullets is in the same place. By having a lot of freebore, you are able to seat the heavy bullets farther out of the so they do not take up much case space. The advantage to a lot of freebore is that you are able to seat the bullets farther out and not take up any more case capacity than a lighter bullet. The downside of a lot of freebore is that if you want to shoot the lighter bullets, they will have a lot of 'jump' before the bullets engages the lands/grooves of the barrel (this can negatively effect accuracy). Given that in 308, bullets range from 155 to 210 grains, it would probably be good to throat your barrel for a 168grain bullet since it's about in the middle and a very common bullet weight for the 308. Make sense? [IMG]http://i342.photobucket.com/albums/o436/mtgrizzard/freeborenn8.jpg[/IMG] Imagine a quarterback throwing a football. Notice that when he throws the ball short distances, the ball does not (nor does it need to) rotate very fast in order to remain stable until the receiver catches the ball. Then imagine a 60 pass where the QB really heaves the ball down the field. Notice how the ball rotates very fast - in order to keep it in stable flight all the way to the receiver. Barrels and bullets work the same way. In order to keep a heavy bullet stable for long distances, it needs to be spinning faster than a lighter bullet. If you're building an all-around rifle in 308, you will want a rate of twist the is fast enough for heavy bullets, yet not so fast that it doesn't over spin the lighter bullets. A good compromise for the 308 is 1:11. Make sense? No worries - always glad to help. It wasn't long ago that I was in your situation and counted on help from this site in order to learn. Keep the questions coming. [/QUOTE]
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.308 Project -seeking advice-
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