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Effects Of Cartridge Over All Length (COAL) And Cartridge Base To Ogive (CBTO) – Part 1
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<blockquote data-quote="Carbine Kid" data-source="post: 1044812" data-attributes="member: 59686"><p>G'day all.</p><p>This subject has prompted me to my first post.</p><p> </p><p>I have been conscious of COL & it's effect on accuracy for quite a while now, first experimenting on an old 26-06 Rem. I suppose this was when the accuracy bug bit. However to this thread.</p><p> </p><p>My main hunting rifle is a Browning Abolt titanium in 300wsm and has two purposes.</p><p>First on pigs, goats, roos, foxes, ie thin skinned targets up to 400m day or night so the Speer 125gn TNT was chosen.</p><p>Second same game out to 1000m plus deer donkey & camel out to 200m so the Speer 180 sp.bt. was chosen for its good BC & suitable construction.</p><p> </p><p>The oal of the 125gn posed no mag length problems and .030 jump was chosen with RL15 & Fed GMM-M. Groups varied from 1.1in @ 3621fps to .27in @ 3454fps. OAL did not need to be altered so a lot of components were saved and .27in load was chosen as 3454fps was considered sufficient.</p><p> </p><p>The 180gn'r at mag length was poor. So OAL's from Kiss to .040 were tried before a powder change. Success came at .025 jump reducing groups from 1.6in worst to .59in. best. RL15 was considered to fast but tried anyway (got heaps), AR 2209 & Win760 were tried with 760 & Fed GMM-M getting the nod. This combo raised velocity from 2860 to 3010.</p><p>So with this projectile the combination of increased case capacity & reduced jump tuned up nicely.</p><p> </p><p>The McMillan 338 Lapua Ackley Imp. was varied from .010 into the lands to .040 off with groups from 2.4in max to one holers of .28in. The best using 104gn Ar 2217, Rocky Mountain 275gnr's for 3164fps & ES of 18fps. I won't try for single figure ES'S as 18fps equates to only 3in @ 1000yd. It's not worth Bbl life and $$$.</p><p> </p><p>All time's wasted whot's not spent shootin.</p><p>Steve</p></blockquote><p></p>
[QUOTE="Carbine Kid, post: 1044812, member: 59686"] G'day all. This subject has prompted me to my first post. I have been conscious of COL & it's effect on accuracy for quite a while now, first experimenting on an old 26-06 Rem. I suppose this was when the accuracy bug bit. However to this thread. My main hunting rifle is a Browning Abolt titanium in 300wsm and has two purposes. First on pigs, goats, roos, foxes, ie thin skinned targets up to 400m day or night so the Speer 125gn TNT was chosen. Second same game out to 1000m plus deer donkey & camel out to 200m so the Speer 180 sp.bt. was chosen for its good BC & suitable construction. The oal of the 125gn posed no mag length problems and .030 jump was chosen with RL15 & Fed GMM-M. Groups varied from 1.1in @ 3621fps to .27in @ 3454fps. OAL did not need to be altered so a lot of components were saved and .27in load was chosen as 3454fps was considered sufficient. The 180gn'r at mag length was poor. So OAL's from Kiss to .040 were tried before a powder change. Success came at .025 jump reducing groups from 1.6in worst to .59in. best. RL15 was considered to fast but tried anyway (got heaps), AR 2209 & Win760 were tried with 760 & Fed GMM-M getting the nod. This combo raised velocity from 2860 to 3010. So with this projectile the combination of increased case capacity & reduced jump tuned up nicely. The McMillan 338 Lapua Ackley Imp. was varied from .010 into the lands to .040 off with groups from 2.4in max to one holers of .28in. The best using 104gn Ar 2217, Rocky Mountain 275gnr's for 3164fps & ES of 18fps. I won't try for single figure ES'S as 18fps equates to only 3in @ 1000yd. It's not worth Bbl life and $$$. All time's wasted whot's not spent shootin. Steve [/QUOTE]
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Effects Of Cartridge Over All Length (COAL) And Cartridge Base To Ogive (CBTO) – Part 1
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