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<blockquote data-quote="Fiftydriver" data-source="post: 75024" data-attributes="member: 10"><p>Jrdoty,</p><p></p><p>Be careful comparing a 200 gr 338 bullet to a 200 gr 7mm bullet. They are extremely different animals to deal with. The baring surface length along is dramatically different for the two bullets.</p><p></p><p>Also remember that in a 338 Lapua loaded with a 200 gr bullet, the powders that you are able to use safely are dramatically faster burning then what can be used in a round like the 7mm Allen Mag. The combination of the faster burn rate powders with the shorter baring surface combine for the ability to get very impressive inital velocities.</p><p></p><p>The key to making a realistic comparision is to get bullets with similiar sectional densities.</p><p></p><p>This is not exact but it gives you an idea what you are comparing. For example, the 200 gr ULD RBBT has a sectional density of .354. For a 338 bullet to equal this it has to weight 285 gr.</p><p></p><p>Now put that into the comparision. How fast will a 338 Lapu drive a bullet with a sectional density of .356 compared to the 7mm Allen Mag velocity with a bullet of the same Sectional density.</p><p></p><p>A 338 Lapua will probably get into the 2800-2900 fps range in a 30" barrel, we are predicting the 7mm Allen Mag will hit 3200 fps with the same barrel length.</p><p></p><p>On top of that compare BC values. A 338 Lapua with a 300 gr ULD or VLD is a 2800 fps round in a 30" barrel and these bullets will have a B.C. in the .790 to .820 range depending on bullet used.</p><p></p><p>The 7mm Allen Mag should hit 3200 fps with a 200 gr ULD RBBT and from eveything we have seen on the computer model projections, this bullet should produce a BC in the high .9 range.</p><p></p><p> As far as the 7mm STW goes, I have yet to see one hit a solid 3200 fps in a 26" barrel with comfortable working pressures and long case life. Add 35 grains of bullet to that and I would bet you would be hard pressed to reach 2850-2900 fps unless your using a bore riding bullet.</p><p></p><p>Also remember that in a relatively small bore like the 7mm shooting 200 gr class bullets, 200-300 fps increases are extremely significant performance boosts.</p><p></p><p>Yes we tend to be conservative but that is only because we want to be honest and practical with you. We see far to many guys listing these extreme velocity numbers for their wildcats only to have their one personal rifle ever come close to those specs.</p><p></p><p>I would rather predict low and have my guys extremely happy that they are getting more from their rifles. So yes we both tend to be on the conservative side on performance predictions and so far all the Allen Mags have outperformed out goals, I hope the 7mm and 338 will be the same.</p><p></p><p>Good Shooting!!</p><p></p><p>Kirby Allen(50)</p></blockquote><p></p>
[QUOTE="Fiftydriver, post: 75024, member: 10"] Jrdoty, Be careful comparing a 200 gr 338 bullet to a 200 gr 7mm bullet. They are extremely different animals to deal with. The baring surface length along is dramatically different for the two bullets. Also remember that in a 338 Lapua loaded with a 200 gr bullet, the powders that you are able to use safely are dramatically faster burning then what can be used in a round like the 7mm Allen Mag. The combination of the faster burn rate powders with the shorter baring surface combine for the ability to get very impressive inital velocities. The key to making a realistic comparision is to get bullets with similiar sectional densities. This is not exact but it gives you an idea what you are comparing. For example, the 200 gr ULD RBBT has a sectional density of .354. For a 338 bullet to equal this it has to weight 285 gr. Now put that into the comparision. How fast will a 338 Lapu drive a bullet with a sectional density of .356 compared to the 7mm Allen Mag velocity with a bullet of the same Sectional density. A 338 Lapua will probably get into the 2800-2900 fps range in a 30" barrel, we are predicting the 7mm Allen Mag will hit 3200 fps with the same barrel length. On top of that compare BC values. A 338 Lapua with a 300 gr ULD or VLD is a 2800 fps round in a 30" barrel and these bullets will have a B.C. in the .790 to .820 range depending on bullet used. The 7mm Allen Mag should hit 3200 fps with a 200 gr ULD RBBT and from eveything we have seen on the computer model projections, this bullet should produce a BC in the high .9 range. As far as the 7mm STW goes, I have yet to see one hit a solid 3200 fps in a 26" barrel with comfortable working pressures and long case life. Add 35 grains of bullet to that and I would bet you would be hard pressed to reach 2850-2900 fps unless your using a bore riding bullet. Also remember that in a relatively small bore like the 7mm shooting 200 gr class bullets, 200-300 fps increases are extremely significant performance boosts. Yes we tend to be conservative but that is only because we want to be honest and practical with you. We see far to many guys listing these extreme velocity numbers for their wildcats only to have their one personal rifle ever come close to those specs. I would rather predict low and have my guys extremely happy that they are getting more from their rifles. So yes we both tend to be on the conservative side on performance predictions and so far all the Allen Mags have outperformed out goals, I hope the 7mm and 338 will be the same. Good Shooting!! Kirby Allen(50) [/QUOTE]
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