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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Range report with 257 and 270 Allen Magnums....
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<blockquote data-quote="Fiftydriver" data-source="post: 59540" data-attributes="member: 10"><p>Brian,</p><p></p><p>All your comments are good ones and things I have been playing with on these case designs.</p><p></p><p>The Rem 700s will accept up to a 3.690 to 3.700" OAL from one rifle to another.</p><p></p><p>I have the 156 gr ULD seated to 3.675" for the rounds I tested. This is slightly off the rifling and with a conventional thin jacketed match bullet in a big cased wildcat with a fast twist barrel this would lead to poor bullet results but with the heavy jackets Richard designed these bullets around, I do not see much problem.</p><p></p><p>I will be doing more testing here as soon as the temps get to where I can do some chrono testing. Will need to determine as well if the 1-8 will stabilize the 156 gr ULD at 500 yards and out. Will report any findings I get.</p><p></p><p>With the 115 gr Ballistic Silvertip, The 257 AM topped out in the 105 gr area in this specific 1-10 Lilja barrel. The 130 gr Wildcat Bonded Core FBHP topped out at 100.0 gr.</p><p></p><p>I would say the load density of the 115 gr loads were in the mid 90% range. The 130 gr were probably around 90% and the 156 were in the mid to high 80% range just estimating right now.</p><p></p><p>The 115 and 130 gr bullets were seated quite deep to help cushion pressure spikes by adding some freebore until I established a starting powder charge basis to work from.</p><p></p><p>The 156 gr pills were seated out further.</p><p></p><p>The 115 and 130s were seated with roughly .575" of bullet shank below the case mouth.</p><p></p><p>The 156 gr had roughly .600" of bullet shank below the case mouth.</p><p></p><p>Again, these are just starting lengths designed to allow me some cushion to control pressures during initial load development. Accuracy loads will be seated out longer, especially with the 115 and 130 gr bullets. The 156, without a stretched mag box is close to the limits of its OAL. Still it is a simple matter to fit a mag box with up to 4.00" OAL.</p><p></p><p>The actual case neck on the 257 AM is .280". I think in my earlier post I stated that I wanted at least one caliber of neck length which is where the .250" may have come up.</p><p></p><p>I would have preferred a neck of .300" to .320" long but the added complexity of case forming would not have been worth the effort. Will marginal, I feel the .280" neck length is plenty for the 257 AM. Of course the 6.5mm and 270 are longer.</p><p></p><p>The 270 AMs neck is right at .285" long.</p><p></p><p>Richard and I are discussing some very interesting bullet designs specifically for the 156 gr class bullet. One design is a double diameter bullet. Similiar to the bore rider designs. This would greatly decrease bore friction, allow higher velocities and less bore fouling. We will see where this testing takes up.</p><p></p><p>I will keep you posted on the results.</p><p></p><p>Good Shooting!!</p><p></p><p>Kirby Allen(50)</p></blockquote><p></p>
[QUOTE="Fiftydriver, post: 59540, member: 10"] Brian, All your comments are good ones and things I have been playing with on these case designs. The Rem 700s will accept up to a 3.690 to 3.700" OAL from one rifle to another. I have the 156 gr ULD seated to 3.675" for the rounds I tested. This is slightly off the rifling and with a conventional thin jacketed match bullet in a big cased wildcat with a fast twist barrel this would lead to poor bullet results but with the heavy jackets Richard designed these bullets around, I do not see much problem. I will be doing more testing here as soon as the temps get to where I can do some chrono testing. Will need to determine as well if the 1-8 will stabilize the 156 gr ULD at 500 yards and out. Will report any findings I get. With the 115 gr Ballistic Silvertip, The 257 AM topped out in the 105 gr area in this specific 1-10 Lilja barrel. The 130 gr Wildcat Bonded Core FBHP topped out at 100.0 gr. I would say the load density of the 115 gr loads were in the mid 90% range. The 130 gr were probably around 90% and the 156 were in the mid to high 80% range just estimating right now. The 115 and 130 gr bullets were seated quite deep to help cushion pressure spikes by adding some freebore until I established a starting powder charge basis to work from. The 156 gr pills were seated out further. The 115 and 130s were seated with roughly .575" of bullet shank below the case mouth. The 156 gr had roughly .600" of bullet shank below the case mouth. Again, these are just starting lengths designed to allow me some cushion to control pressures during initial load development. Accuracy loads will be seated out longer, especially with the 115 and 130 gr bullets. The 156, without a stretched mag box is close to the limits of its OAL. Still it is a simple matter to fit a mag box with up to 4.00" OAL. The actual case neck on the 257 AM is .280". I think in my earlier post I stated that I wanted at least one caliber of neck length which is where the .250" may have come up. I would have preferred a neck of .300" to .320" long but the added complexity of case forming would not have been worth the effort. Will marginal, I feel the .280" neck length is plenty for the 257 AM. Of course the 6.5mm and 270 are longer. The 270 AMs neck is right at .285" long. Richard and I are discussing some very interesting bullet designs specifically for the 156 gr class bullet. One design is a double diameter bullet. Similiar to the bore rider designs. This would greatly decrease bore friction, allow higher velocities and less bore fouling. We will see where this testing takes up. I will keep you posted on the results. Good Shooting!! Kirby Allen(50) [/QUOTE]
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Range report with 257 and 270 Allen Magnums....
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