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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Boosting BC of commerical bullets.....
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<blockquote data-quote="royinidaho" data-source="post: 780611" data-attributes="member: 2011"><p>Kirby,</p><p></p><p>You and I seem to be a lot alike when it comes to getting all of the bc possible,</p><p></p><p>The differences between you and I are that you have skill, experience, talent, equipment and an uncanny knack for bringing these together with near magical results. However, I do think that I have it on you in the 'looks' area. <img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite8" alt=":D" title="Big Grin :D" loading="lazy" data-shortname=":D" /><img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite8" alt=":D" title="Big Grin :D" loading="lazy" data-shortname=":D" /></p><p></p><p>I knew nothing about machining. Still don't. But have learned a tone making buckets and buckets if chips. Both aluminum and brass.</p><p></p><p>I bought me a HF 8x14 bench lathe and ruined a set of jaws getting +/- 0.00001 run out. But I got zero runout. Good start.<img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite11" alt=":rolleyes:" title="Roll Eyes :rolleyes:" loading="lazy" data-shortname=":rolleyes:" /></p><p></p><p>Objective was to get bullets worthy of use in one of your 270 AMs. </p><p></p><p>First attempt was to stage 7MM Berger's to .277. Corbin made me a die. He said that it was too much swage but to know I'd have to try. I tried. It didn't work. Typical for me.</p><p></p><p>Running Dan Lilja's bc spread sheet said thar simply increasing length without increasing weight wouldn't get me a significant bc increase.</p><p></p><p>That's when I got the lathe and came up with a tip design to fit the 270 NAB and Ballistic tip. I chips quite a few feet if brass rod before converting the lathe to CNC to get some thru put. used LEGOs Mindstorms components for then CNC. Laugh if you wish. But it worked. <img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite8" alt=":D" title="Big Grin :D" loading="lazy" data-shortname=":D" /></p><p></p><p>Tips were well within my very tight specs. However without an automatic feed, even w/CNC it was too slow to pencil out.</p><p></p><p>A commercial bit was $15,000.00 minimum order. Well out of reach to get a $0.15 Point.</p><p></p><p>Kevin Cram made up a very well working meplat trimmer which allowed a very straight face for the tip to butt against and a uniform length which was critical for proper seating of the tip.</p><p></p><p>Eaglet's computer calcs said the bc was increased from 0.497 to probably 0.658. Significant! Never got to confirm.</p><p></p><p>Bullet weight increased from 150 to nearly 160 grains. Length of the tipped 150 NBT/NAB was right there with Richard's 195 WC.</p><p></p><p>End result was thar re-tipped Noslers shot along with the originals which is very well in this rifle.</p><p></p><p>The down side was that less than 20% of the tips passed my quality control. <img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite11" alt=":rolleyes:" title="Roll Eyes :rolleyes:" loading="lazy" data-shortname=":rolleyes:" /></p><p></p><p>I've come up with several hundred of Richard's originals, 150Bergers shoot very well in this barrel and Berger announced imminent release of a 170 gr offering which pretty much quenched my motivation.</p><p></p><p>Reason for the low QC results was flexing of the 3/16" brass rod. The steady rest was almost 1" from the chuck jaws which, unless I had the cutter ground exactly correct and took very small cuts there was a very small flex in the rod. This flex was hard to detect but raised its ugly head at the 200 yard target.</p><p></p><p>I think I ran out of persistence with the 277 project.</p><p></p><p>I do have that 375 AM which sucks me back in this realm. I went with the 375 vs the 338 with the thought that one day there would be a bullet that would raise 375 AM performance to its proper position ABOVE its little brother. The 338 AM. <img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite8" alt=":D" title="Big Grin :D" loading="lazy" data-shortname=":D" /></p></blockquote><p></p>
[QUOTE="royinidaho, post: 780611, member: 2011"] Kirby, You and I seem to be a lot alike when it comes to getting all of the bc possible, The differences between you and I are that you have skill, experience, talent, equipment and an uncanny knack for bringing these together with near magical results. However, I do think that I have it on you in the 'looks' area. :D:D I knew nothing about machining. Still don't. But have learned a tone making buckets and buckets if chips. Both aluminum and brass. I bought me a HF 8x14 bench lathe and ruined a set of jaws getting +/- 0.00001 run out. But I got zero runout. Good start.:rolleyes: Objective was to get bullets worthy of use in one of your 270 AMs. First attempt was to stage 7MM Berger's to .277. Corbin made me a die. He said that it was too much swage but to know I'd have to try. I tried. It didn't work. Typical for me. Running Dan Lilja's bc spread sheet said thar simply increasing length without increasing weight wouldn't get me a significant bc increase. That's when I got the lathe and came up with a tip design to fit the 270 NAB and Ballistic tip. I chips quite a few feet if brass rod before converting the lathe to CNC to get some thru put. used LEGOs Mindstorms components for then CNC. Laugh if you wish. But it worked. :D Tips were well within my very tight specs. However without an automatic feed, even w/CNC it was too slow to pencil out. A commercial bit was $15,000.00 minimum order. Well out of reach to get a $0.15 Point. Kevin Cram made up a very well working meplat trimmer which allowed a very straight face for the tip to butt against and a uniform length which was critical for proper seating of the tip. Eaglet's computer calcs said the bc was increased from 0.497 to probably 0.658. Significant! Never got to confirm. Bullet weight increased from 150 to nearly 160 grains. Length of the tipped 150 NBT/NAB was right there with Richard's 195 WC. End result was thar re-tipped Noslers shot along with the originals which is very well in this rifle. The down side was that less than 20% of the tips passed my quality control. :rolleyes: I've come up with several hundred of Richard's originals, 150Bergers shoot very well in this barrel and Berger announced imminent release of a 170 gr offering which pretty much quenched my motivation. Reason for the low QC results was flexing of the 3/16" brass rod. The steady rest was almost 1" from the chuck jaws which, unless I had the cutter ground exactly correct and took very small cuts there was a very small flex in the rod. This flex was hard to detect but raised its ugly head at the 200 yard target. I think I ran out of persistence with the 277 project. I do have that 375 AM which sucks me back in this realm. I went with the 375 vs the 338 with the thought that one day there would be a bullet that would raise 375 AM performance to its proper position ABOVE its little brother. The 338 AM. :D [/QUOTE]
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Boosting BC of commerical bullets.....
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