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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
New GSC 338 LRH bullets.
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<blockquote data-quote="BryanLitz" data-source="post: 1046962" data-attributes="member: 7848"><p>Mr Schultz,</p><p></p><p>My BC's have units of lb/in^2 which is the universal standard in the small arms industry even for countries which primarily operate in metric. If your BC's are expressed in units other than lb/in^2, then please say so. </p><p></p><p>While we're clarifying such things, when we talk about G1 BC's, what I mean is, BC's referenced to the G1 drag standard; A poor choice for modern LR bullets, but since that's all you show for your bullets, it's our only common language for performance measure. Here's a representation of the G1 model I use: <a href="http://www.jbmballistics.com/ballistics/downloads/text/mcg1.txt" target="_blank">http://www.jbmballistics.com/ballistics/downloads/text/mcg1.txt</a></p><p></p><p>This is the G1 drag model that ballistics programs use when you enter a G1 BC. If you're using a different G1 model, please say so.</p><p></p><p>Furthermore, my BC's are corrected to standard ICAO sea level atmosphere. This is the international standard atmosphere model. If you're referencing a different atmosphere model, please say so.</p><p></p><p>Of course none of the above potential misunderstandings explain why my measured BC's would be so much lower than your predicted BC's. See below example of your .375 cal 355 grain SP. I chose this bullet because it was tested in a 1:10.5" twist rate that produces your recommended SG of 1.2+. In my test conditions, the SG was actually 1.67. It was even one of the cartridges you recommend: .375 CT.</p><p></p><p><img src="http://appliedballisticsllc.com/images/GS375cal355gr.bmp" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p><p></p><p>As you can see, the measured BC falls short of your predicted value at all speeds. Yes, the error changes with speed, and I can see your issue with averaging BC's especially G1 BC's. G7 BC's are not perfect for your bullets, but they're much better than G1's in most cases. But you don't provide G7 BC's, so averaging is a bigger problem than it has to be. However, that's not the big picture here. </p><p></p><p>The big picture is that you're way over representing the actual performance of your bullets.</p><p></p><p>-Bryan</p></blockquote><p></p>
[QUOTE="BryanLitz, post: 1046962, member: 7848"] Mr Schultz, My BC's have units of lb/in^2 which is the universal standard in the small arms industry even for countries which primarily operate in metric. If your BC's are expressed in units other than lb/in^2, then please say so. While we're clarifying such things, when we talk about G1 BC's, what I mean is, BC's referenced to the G1 drag standard; A poor choice for modern LR bullets, but since that's all you show for your bullets, it's our only common language for performance measure. Here's a representation of the G1 model I use: [url]http://www.jbmballistics.com/ballistics/downloads/text/mcg1.txt[/url] This is the G1 drag model that ballistics programs use when you enter a G1 BC. If you're using a different G1 model, please say so. Furthermore, my BC's are corrected to standard ICAO sea level atmosphere. This is the international standard atmosphere model. If you're referencing a different atmosphere model, please say so. Of course none of the above potential misunderstandings explain why my measured BC's would be so much lower than your predicted BC's. See below example of your .375 cal 355 grain SP. I chose this bullet because it was tested in a 1:10.5" twist rate that produces your recommended SG of 1.2+. In my test conditions, the SG was actually 1.67. It was even one of the cartridges you recommend: .375 CT. [IMG]http://appliedballisticsllc.com/images/GS375cal355gr.bmp[/IMG] As you can see, the measured BC falls short of your predicted value at all speeds. Yes, the error changes with speed, and I can see your issue with averaging BC's especially G1 BC's. G7 BC's are not perfect for your bullets, but they're much better than G1's in most cases. But you don't provide G7 BC's, so averaging is a bigger problem than it has to be. However, that's not the big picture here. The big picture is that you're way over representing the actual performance of your bullets. -Bryan [/QUOTE]
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Rifles, Reloading, Optics, Equipment
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New GSC 338 LRH bullets.
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