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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Potential downsides to fast twist barrel?
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<blockquote data-quote="J E Custom" data-source="post: 1841009" data-attributes="member: 2736"><p>I also built a 7 STW For speed that had a 31" barrel. it had a 1 in 9 twist and was a 6 grove Lilja.</p><p> It was intended to shoot 140 grain bullets at blazing speeds and flat trajectories. </p><p></p><p>As I worked up to top velocities It got better and better until I reached 3800 ft/sec, then things went south, I backed off and regained the accuracy at just over 3750 ft/sec. so I decided to do a impact test at 100 yards to 600 yards to see if I could find the problem. (I still wasn't getting high pressure signs).</p><p></p><p>It all came to light at 100 yards. I was throwing the jackets at the muzzle. it was very clear with two odd looking holes in the target, I tried the 3700 ft/loads and they produced beautiful little bug hole groups. I also did my digging trick in the berm to try and recover a decent bullet to look at the engraving. I did find a few but they were well destroyed, so no real rifle engraving results.</p><p></p><p>With jacket loss I decided the same as many others have suggested and went to a mono metal bullet. They held up well but I could never get the accuracy out of them because apparently I was reaching near 400,000 RPM and there balance was not perfect (To bad Hammer Bullets were not around at the time). After realizing I had reached the bullets limit, I backed off to 3700 ft/sec velocities and they performed well. The longest shot that I made with this rifle and load was just over 800 yards and the hog looked like he was hit by lightning.</p><p></p><p>I did recover some of these bullets from this load and the engraving on the bullets looked great with the 6 grove barrel. I have many 3 grove barrels that perform well but they are slower twist at higher velocities and most bullets are able to handle the velocity in the slower twist, The only rifle that reached bullet destruction at/in the barrel is a 223 wssm in a 1 in 15 twist @ 4600+ft/sec velocity.</p><p></p><p>So depending on what velocity and caliber you choose, twist rate and grove count can be important for best performance. </p><p></p><p>Chose wisely!!.</p><p></p><p>J E CUSTOM</p></blockquote><p></p>
[QUOTE="J E Custom, post: 1841009, member: 2736"] I also built a 7 STW For speed that had a 31" barrel. it had a 1 in 9 twist and was a 6 grove Lilja. It was intended to shoot 140 grain bullets at blazing speeds and flat trajectories. As I worked up to top velocities It got better and better until I reached 3800 ft/sec, then things went south, I backed off and regained the accuracy at just over 3750 ft/sec. so I decided to do a impact test at 100 yards to 600 yards to see if I could find the problem. (I still wasn't getting high pressure signs). It all came to light at 100 yards. I was throwing the jackets at the muzzle. it was very clear with two odd looking holes in the target, I tried the 3700 ft/loads and they produced beautiful little bug hole groups. I also did my digging trick in the berm to try and recover a decent bullet to look at the engraving. I did find a few but they were well destroyed, so no real rifle engraving results. With jacket loss I decided the same as many others have suggested and went to a mono metal bullet. They held up well but I could never get the accuracy out of them because apparently I was reaching near 400,000 RPM and there balance was not perfect (To bad Hammer Bullets were not around at the time). After realizing I had reached the bullets limit, I backed off to 3700 ft/sec velocities and they performed well. The longest shot that I made with this rifle and load was just over 800 yards and the hog looked like he was hit by lightning. I did recover some of these bullets from this load and the engraving on the bullets looked great with the 6 grove barrel. I have many 3 grove barrels that perform well but they are slower twist at higher velocities and most bullets are able to handle the velocity in the slower twist, The only rifle that reached bullet destruction at/in the barrel is a 223 wssm in a 1 in 15 twist @ 4600+ft/sec velocity. So depending on what velocity and caliber you choose, twist rate and grove count can be important for best performance. Chose wisely!!. J E CUSTOM [/QUOTE]
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Potential downsides to fast twist barrel?
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