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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Hexagonal Boron Nitride
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<blockquote data-quote="Pdvdh" data-source="post: 1080089" data-attributes="member: 4191"><p>In my Brux 28" .280 RCBS Improved 30-degree (similar powder capacity as .280 AI), it required a <strong>0.5%</strong> increased powder charge of IMR 7828SSC with HBN coated bullets to regain the original muzzle velocity I had been shooting with uncoated 160gr Nosler Accubonds. Increased powder charge from 58.4 to 58.7gr IMR 7828SSC.</p><p></p><p>It also required a <strong>0.5%</strong> increased powder charge of H1000 with HBN coated bullets to regain the original muzzle velocity I had been shooting with the uncoated 162gr A-Max. Increased powder charge from 62.4 to 62.7gr H1000.</p><p></p><p>I reduced my original powder charge with the freshly coated HBN bore from 62.4 to 61.5gr H1000 with the 162 A-Max. That was plenty of reduction in powder to prevent overpressure on the HBN coated bore with the first HBN coated bullet. My MV dropped about 70fps. It would be wise to reduce your powder charge a bit when firing the first bullet down an HBN coated bore should you coat your bore with HBN. After the first reduced charge/bullet fired, I ramped right back up to maximum loads and then a bit more to regain my original MVs.</p><p></p><p>My 25.5" Lilja 300 Win Mag required an increase of <strong>0.8%</strong> IMR 7828 with HBN coated bullets to regain the original MV I had been shooting with the uncoated 210gr Berger VLDs. Increased powder charge from 73.3 to 73.9gr 7828.</p><p></p><p>This provides an idea of the increase in powder it will require to regain your original MV should you start shooting HBN coated bullets.</p></blockquote><p></p>
[QUOTE="Pdvdh, post: 1080089, member: 4191"] In my Brux 28" .280 RCBS Improved 30-degree (similar powder capacity as .280 AI), it required a [B]0.5%[/B] increased powder charge of IMR 7828SSC with HBN coated bullets to regain the original muzzle velocity I had been shooting with uncoated 160gr Nosler Accubonds. Increased powder charge from 58.4 to 58.7gr IMR 7828SSC. It also required a [B]0.5%[/B] increased powder charge of H1000 with HBN coated bullets to regain the original muzzle velocity I had been shooting with the uncoated 162gr A-Max. Increased powder charge from 62.4 to 62.7gr H1000. I reduced my original powder charge with the freshly coated HBN bore from 62.4 to 61.5gr H1000 with the 162 A-Max. That was plenty of reduction in powder to prevent overpressure on the HBN coated bore with the first HBN coated bullet. My MV dropped about 70fps. It would be wise to reduce your powder charge a bit when firing the first bullet down an HBN coated bore should you coat your bore with HBN. After the first reduced charge/bullet fired, I ramped right back up to maximum loads and then a bit more to regain my original MVs. My 25.5" Lilja 300 Win Mag required an increase of [B]0.8%[/B] IMR 7828 with HBN coated bullets to regain the original MV I had been shooting with the uncoated 210gr Berger VLDs. Increased powder charge from 73.3 to 73.9gr 7828. This provides an idea of the increase in powder it will require to regain your original MV should you start shooting HBN coated bullets. [/QUOTE]
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