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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Meplat dia vs BC
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<blockquote data-quote="Darkker" data-source="post: 1167182" data-attributes="member: 81406"><p>1 - Yes, Just because a former powder tech for General Dynamics(Emary) finally gets the toys everyone else has used, doesn't suddenly make him a genius with bullets either; even if he writes it down in a book.</p><p></p><p>2- No, not so much. This topic aside, you really should read his book; very good stuff!</p><p></p><p>Now lets run some calcs:</p><p>Horn-head loves to talk in the white paper about the 300 WM, Well lets use some over-loads.</p><p></p><p>Elevation - 850 feet</p><p>Air temp - 55 deg. F</p><p>Humidity - 35%</p><p>ICAO Std</p><p>Zero - 100 yards</p><p>Wind - 10mph</p><p>Angle - 90 deg</p><p>Baro - 29.92 "</p><p>Units in Mils</p><p>No spin drift / Coriolis</p><p>Muzzle Velocity - 3,100 fps</p><p></p><p>208gr "Melty"-max, Litz tested G7 of 0.324</p><p>100 - U-0, R 0.1 mil Vel - 2952.7 </p><p>1,000 - U- 6.4, R1.5 Vel - 1796.9</p><p></p><p>212gr ELD-X. Hornady claimed G7 of 0.336</p><p>100 - U-0, R-0.1 Vel - 2957.8</p><p>1,000 - U- 6.3, R- 1.4 Vel - 1837.0</p><p></p><p></p><p></p><p>So what do we see? 0.1 mil difference, which if you talk to the PRS boys; 0.1 - 0.2 mils is typical gain from tipping bullets.</p><p>So what does this mean? Here is what I see.</p><p></p><p> There is no PRACTICAL difference for anyone EXCEPT the worlds greatest shooters. At 1,000 I argue that that tight is even repeatable for them. There is in fact a difference, just not anything practical. And Vaughn's work showed this already. The tip DOES affect the BC, but again, it isn't a significant amount compared to what the Ogive and Tail angle contribute. For a more recent example of this, look at the original 168gr SMK that tumbled at Camp Perry long ago. That had a CG/CP issue going against it, BUT it was the 13 deg. tail angle that did it in. That tail angle gave it a super-swinging-sexy BC. As Dr. McCoy's work showed, that ain't going to cut the mustard when it comes time to cross trans-sonic.</p><p></p><p>Now why there is no difference is where you can pick your poison:</p><p>Now is the tip ACTUALLY melting? I have NFC. But when using Litz's G7 number, which is the appropriate measurement of this type of bullet; we can conclude one of the following:</p><p>1 - It IS melting, but is irrelevant.</p><p>2 - it ISN'T melting, and is irrelevant.</p><p></p><p>My tinfoil-hat view is: Hornady quickly realized that their use of a single inflated G1, isn't appropriate. They noticed "something was wrong". Was it a melty tip? Don't know, but as we now know, it doesn't matter.</p><p>This whole Tip-Gate nonsense is a stab at who they now see as an easy target, Nosler. As Litz has shown many times, Nosler is the worst offender when it comes to inflating G1 numbers. They also have a highly sought-after Crap-U-Bond Long Range bullet. What better way to stick a knife in their side, and disguise the 30% price hike for a slight redesign?</p></blockquote><p></p>
[QUOTE="Darkker, post: 1167182, member: 81406"] 1 - Yes, Just because a former powder tech for General Dynamics(Emary) finally gets the toys everyone else has used, doesn't suddenly make him a genius with bullets either; even if he writes it down in a book. 2- No, not so much. This topic aside, you really should read his book; very good stuff! Now lets run some calcs: Horn-head loves to talk in the white paper about the 300 WM, Well lets use some over-loads. Elevation - 850 feet Air temp - 55 deg. F Humidity - 35% ICAO Std Zero - 100 yards Wind - 10mph Angle - 90 deg Baro - 29.92 " Units in Mils No spin drift / Coriolis Muzzle Velocity - 3,100 fps 208gr "Melty"-max, Litz tested G7 of 0.324 100 - U-0, R 0.1 mil Vel - 2952.7 1,000 - U- 6.4, R1.5 Vel - 1796.9 212gr ELD-X. Hornady claimed G7 of 0.336 100 - U-0, R-0.1 Vel - 2957.8 1,000 - U- 6.3, R- 1.4 Vel - 1837.0 So what do we see? 0.1 mil difference, which if you talk to the PRS boys; 0.1 - 0.2 mils is typical gain from tipping bullets. So what does this mean? Here is what I see. There is no PRACTICAL difference for anyone EXCEPT the worlds greatest shooters. At 1,000 I argue that that tight is even repeatable for them. There is in fact a difference, just not anything practical. And Vaughn's work showed this already. The tip DOES affect the BC, but again, it isn't a significant amount compared to what the Ogive and Tail angle contribute. For a more recent example of this, look at the original 168gr SMK that tumbled at Camp Perry long ago. That had a CG/CP issue going against it, BUT it was the 13 deg. tail angle that did it in. That tail angle gave it a super-swinging-sexy BC. As Dr. McCoy's work showed, that ain't going to cut the mustard when it comes time to cross trans-sonic. Now why there is no difference is where you can pick your poison: Now is the tip ACTUALLY melting? I have NFC. But when using Litz's G7 number, which is the appropriate measurement of this type of bullet; we can conclude one of the following: 1 - It IS melting, but is irrelevant. 2 - it ISN'T melting, and is irrelevant. My tinfoil-hat view is: Hornady quickly realized that their use of a single inflated G1, isn't appropriate. They noticed "something was wrong". Was it a melty tip? Don't know, but as we now know, it doesn't matter. This whole Tip-Gate nonsense is a stab at who they now see as an easy target, Nosler. As Litz has shown many times, Nosler is the worst offender when it comes to inflating G1 numbers. They also have a highly sought-after Crap-U-Bond Long Range bullet. What better way to stick a knife in their side, and disguise the 30% price hike for a slight redesign? [/QUOTE]
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