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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Is this a typo?
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<blockquote data-quote="Jeff In TX" data-source="post: 144612" data-attributes="member: 1522"><p><strong>No it\'s not a typo</strong></p><p></p><p>I'm going to jump into this one with both feet...**** why can't I leave well enough alone!</p><p></p><p>IMHO, what the Sierra ballistic engineers put into their ballistic calculator is the wrong way to calculate ballistics. First they started with a G1 ballistic model by a Russian Col Ingalls Mayevski that is well over a hundred years old and is based on a 1", one pound round nose projectile. What a great foundation for to calculate today's modern flat base spire point, boat tail and VLD type bullets. The other reason they chose the G1 ballistic model is because it yields higher BC's for bullets. The theory is, the higher the BC the more bullets we'll sell.</p><p></p><p>Anyhow to get around the short comings of this century old calculation, they had to learn to massage that ballistic model to get better long distance accuracy out of their program. They did this by using multiple BC's that can go up and down as the velocity decreases.</p><p></p><p>The US Army at the Aberdeen proving grounds have mathematically worked out more efficient ballistic models which don't use G1 BC's for bullets. CD's are much more accurate, but having said that for small arms the G5 (standard boat tail), G6 (flat base Spire point), and G7 (VLD) ballistic models are hands down more accurate than what Sierra is trying to push. Some of today's better ballistic programs such as the RSI Shooting lab support those other models.</p><p></p><p>Think about this, they are using the same ballistic model for any type of bullet. So all types of bullets no matter their design will have the same flight/ballistic characteristics…NOT!</p><p></p><p>A Sierra .308 175 grain BTHP has a published G1 BC of .505. The actual G5 BC for this bullet .316. Lower BC's don't sell well, but the mathematical calculations used for the G5 ballistic model are extremely accurate, a lot more so than that massaged G1 stuff they're putting out.</p><p></p><p>Off my soap box, now let the flood gates open…**** why couldn't I just have left well enough a lone???</p></blockquote><p></p>
[QUOTE="Jeff In TX, post: 144612, member: 1522"] [b]No it\'s not a typo[/b] I'm going to jump into this one with both feet...**** why can't I leave well enough alone! IMHO, what the Sierra ballistic engineers put into their ballistic calculator is the wrong way to calculate ballistics. First they started with a G1 ballistic model by a Russian Col Ingalls Mayevski that is well over a hundred years old and is based on a 1”, one pound round nose projectile. What a great foundation for to calculate today’s modern flat base spire point, boat tail and VLD type bullets. The other reason they chose the G1 ballistic model is because it yields higher BC’s for bullets. The theory is, the higher the BC the more bullets we’ll sell. Anyhow to get around the short comings of this century old calculation, they had to learn to massage that ballistic model to get better long distance accuracy out of their program. They did this by using multiple BC’s that can go up and down as the velocity decreases. The US Army at the Aberdeen proving grounds have mathematically worked out more efficient ballistic models which don’t use G1 BC’s for bullets. CD’s are much more accurate, but having said that for small arms the G5 (standard boat tail), G6 (flat base Spire point), and G7 (VLD) ballistic models are hands down more accurate than what Sierra is trying to push. Some of today’s better ballistic programs such as the RSI Shooting lab support those other models. Think about this, they are using the same ballistic model for any type of bullet. So all types of bullets no matter their design will have the same flight/ballistic characteristics…NOT! A Sierra .308 175 grain BTHP has a published G1 BC of .505. The actual G5 BC for this bullet .316. Lower BC’s don’t sell well, but the mathematical calculations used for the G5 ballistic model are extremely accurate, a lot more so than that massaged G1 stuff they’re putting out. Off my soap box, now let the flood gates open…**** why couldn’t I just have left well enough a lone??? [/QUOTE]
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