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Drop in Velocity?
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<blockquote data-quote="Fiftydriver" data-source="post: 60051" data-attributes="member: 10"><p>Bcraft1111,</p><p></p><p>What I ment by "shorter then standard" is that a standard full length magnum runs 2.850" in case length. The big magnums like the 30-378 and Rigby will run 2.910" long. </p><p></p><p>I did not realize the Warbird was actually 2.800" long. Still it is shorter then the standard 2.850" standard magnum length brass allowing even more room in a conventional length Mag box.</p><p></p><p>The X bullets generally need to get a run at the rifling to have any consistancy at all. Most often an X bullet seated to close to the rifling will result in pressure variations that show up in velocity spreads.</p><p></p><p>This is really the opposite compared to a conventional bullet design. Unfortunately, while the velocity spreads may decrease with a longer jump to the rifling with the X bullet, often the group size increases.</p><p></p><p>For a pillar bedded rifle, 65 in/lbs is the correct torque. For some composite stocks this is to much and they will get springy.</p><p></p><p>This is far to much for a traditional wood stock, even a properly glass bedded stock as this amount of pressure will compress the wood significantly.</p><p></p><p>I would recommend contacting Lazzeroni and finding out what torque specs they recommend for their rifle. If it is pillar bedded, I would use 65 in/lbs.</p><p></p><p>If you do decide to rebarrel, the 1-12 twist will actually stabilize a 200 gr Accubond, I have seen it at 200 yards. The rifle was printing 1 1/4" groups at 200 yards. Not great but not bad either.</p><p></p><p>Still, I would go with the standard 1-10 twist simply because it give so much great flexibility in which bullets you can use. There is no doubt the 1-10 twist barrels would stabilize any bullets up to a 220 gr Sierra MK or 210 gr Berger VLD even in the coldest temps.</p><p></p><p>They also shoot the lighter bullets extremely well if you choose to do so. I am in total agreement with Brian about the use of heavy bullets in this class of round. Once you get to the point where you can get 100 gr of powder under a 30 caliber bullet, there is no point in using anything less then 180 gr bullets and yes, the 200 gr bullets are even a better balance for the Warbirds case capacity.</p><p></p><p>My brothers rifle shot the 200 gr Accubonds very well with Retumbo and topped 3200 fps easily with this bullet. I believe he was puching 3300 fps with top safe loads.</p><p></p><p>As far as barrel length, that is a personal preference. I like long barrels on my big game rifles and especiially my extreme range rifles. But I hunt in very wide open big country here in central Montana where a long barrel is more of an advantage then a disadvantage.</p><p></p><p>If I were building myseld a rifle like around the Warbird, I would use a #7 contour Lilja 3 groove, 1-10" barrel and flute it with the large diameter .312" 50 BMG style flutes with a finish length of 30".</p><p></p><p>This would give me the stiffness of a .825" diameter muzzle but with the weight of a relatively slim #6 contour. Properly set up I would imagine you would be getting +3600 fps with the 180 gr Accubond and groups would be in the 1/2 moa range or less.</p><p></p><p>Better yet, you could drive the 200 gr Accubonds to 3400 fps and with a quality brake such as the Holland Quick Discharge brake, recoil would feel about like a 308 Win in a heavy rifle.</p><p></p><p>That is just what I would do but again I like the feel of a 30" sporter rifle as all my shots are off bipods or bags. No offhanding for this kid.</p><p></p><p>Have a good one,</p><p></p><p>Kirby Allen(50)</p></blockquote><p></p>
[QUOTE="Fiftydriver, post: 60051, member: 10"] Bcraft1111, What I ment by "shorter then standard" is that a standard full length magnum runs 2.850" in case length. The big magnums like the 30-378 and Rigby will run 2.910" long. I did not realize the Warbird was actually 2.800" long. Still it is shorter then the standard 2.850" standard magnum length brass allowing even more room in a conventional length Mag box. The X bullets generally need to get a run at the rifling to have any consistancy at all. Most often an X bullet seated to close to the rifling will result in pressure variations that show up in velocity spreads. This is really the opposite compared to a conventional bullet design. Unfortunately, while the velocity spreads may decrease with a longer jump to the rifling with the X bullet, often the group size increases. For a pillar bedded rifle, 65 in/lbs is the correct torque. For some composite stocks this is to much and they will get springy. This is far to much for a traditional wood stock, even a properly glass bedded stock as this amount of pressure will compress the wood significantly. I would recommend contacting Lazzeroni and finding out what torque specs they recommend for their rifle. If it is pillar bedded, I would use 65 in/lbs. If you do decide to rebarrel, the 1-12 twist will actually stabilize a 200 gr Accubond, I have seen it at 200 yards. The rifle was printing 1 1/4" groups at 200 yards. Not great but not bad either. Still, I would go with the standard 1-10 twist simply because it give so much great flexibility in which bullets you can use. There is no doubt the 1-10 twist barrels would stabilize any bullets up to a 220 gr Sierra MK or 210 gr Berger VLD even in the coldest temps. They also shoot the lighter bullets extremely well if you choose to do so. I am in total agreement with Brian about the use of heavy bullets in this class of round. Once you get to the point where you can get 100 gr of powder under a 30 caliber bullet, there is no point in using anything less then 180 gr bullets and yes, the 200 gr bullets are even a better balance for the Warbirds case capacity. My brothers rifle shot the 200 gr Accubonds very well with Retumbo and topped 3200 fps easily with this bullet. I believe he was puching 3300 fps with top safe loads. As far as barrel length, that is a personal preference. I like long barrels on my big game rifles and especiially my extreme range rifles. But I hunt in very wide open big country here in central Montana where a long barrel is more of an advantage then a disadvantage. If I were building myseld a rifle like around the Warbird, I would use a #7 contour Lilja 3 groove, 1-10" barrel and flute it with the large diameter .312" 50 BMG style flutes with a finish length of 30". This would give me the stiffness of a .825" diameter muzzle but with the weight of a relatively slim #6 contour. Properly set up I would imagine you would be getting +3600 fps with the 180 gr Accubond and groups would be in the 1/2 moa range or less. Better yet, you could drive the 200 gr Accubonds to 3400 fps and with a quality brake such as the Holland Quick Discharge brake, recoil would feel about like a 308 Win in a heavy rifle. That is just what I would do but again I like the feel of a 30" sporter rifle as all my shots are off bipods or bags. No offhanding for this kid. Have a good one, Kirby Allen(50) [/QUOTE]
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