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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Speer 165 Spitzer BTSP
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<blockquote data-quote="Top Cat" data-source="post: 565739" data-attributes="member: 4532"><p>Many of the published BC numbers for Speer bullets appear to be over stated.</p><p></p><p>Of course, you're putting a lot of faith in assuming that the published G1 BC for that bullet is correct, and since Speer offers no info as to how BC was determined, or at what velocity range it is supposed to be accurate, it's really not very useful in predicting long range results. </p><p></p><p>At best, a single G1 BC number is well known to not be accurate over the range of a bullet's flight.</p><p></p><p>Possibly, they determined BC by modeling rather than by real world testing. Bullet manufacturers used to use modeling in the past to estimate BC until they expanded their ballistics capability. It's very expensive to do real world BC testing, but it's necessary, because the theoretically obtained BC values often differ dramatically from real world values. </p><p></p><p>As a result, recently, a lot of previously published BC estimates were dramatically lowered when their bullets were actually tested. The changes were reflected in revised published data from Sierra, Barnes, Hornady, Berger to name a few, and I don't know if Speer actually bothered to test their bullets or not. Some manufacturers only test their Match bullets because BC matters more to match shooters.</p><p></p><p>In their 1994 Manual, Speer published a BC of .477 for that bullet, so how did it happen to grow over time...benefits of ageing like fine wine perhaps?</p><p></p><p>I may have some of those bullets laying around here, and if I do I'll take a look at them, but it's not reasonable to me that an older basic hunting design would exceed the best contemporary VLD designs of the same weight. </p><p></p><p>In any event, I wouldn't depend on un-tested G1 BC numbers to reflect actual range results in the field. </p><p></p><p>If their BC numbers were that high, LR shooters would be raving about the Speer miracle bullets and shooting them...I don't see that happening.</p><p></p><p>TC</p></blockquote><p></p>
[QUOTE="Top Cat, post: 565739, member: 4532"] Many of the published BC numbers for Speer bullets appear to be over stated. Of course, you're putting a lot of faith in assuming that the published G1 BC for that bullet is correct, and since Speer offers no info as to how BC was determined, or at what velocity range it is supposed to be accurate, it's really not very useful in predicting long range results. At best, a single G1 BC number is well known to not be accurate over the range of a bullet's flight. Possibly, they determined BC by modeling rather than by real world testing. Bullet manufacturers used to use modeling in the past to estimate BC until they expanded their ballistics capability. It's very expensive to do real world BC testing, but it's necessary, because the theoretically obtained BC values often differ dramatically from real world values. As a result, recently, a lot of previously published BC estimates were dramatically lowered when their bullets were actually tested. The changes were reflected in revised published data from Sierra, Barnes, Hornady, Berger to name a few, and I don't know if Speer actually bothered to test their bullets or not. Some manufacturers only test their Match bullets because BC matters more to match shooters. In their 1994 Manual, Speer published a BC of .477 for that bullet, so how did it happen to grow over time...benefits of ageing like fine wine perhaps? I may have some of those bullets laying around here, and if I do I'll take a look at them, but it's not reasonable to me that an older basic hunting design would exceed the best contemporary VLD designs of the same weight. In any event, I wouldn't depend on un-tested G1 BC numbers to reflect actual range results in the field. If their BC numbers were that high, LR shooters would be raving about the Speer miracle bullets and shooting them...I don't see that happening. TC [/QUOTE]
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Speer 165 Spitzer BTSP
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