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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
So Will the .270 Win Overtake the CM's and PRC's?
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<blockquote data-quote="TX Badger" data-source="post: 1954323" data-attributes="member: 95235"><p>If you are only considering what is commonly avail., you are correct. If you hamstring the .277 with a 1:10 then yes. If you want to compare a sammi spec chamber from the 30s to something more modern then yes, a long heavy for caliber bullet can be an issue. Maybe we are just differing on the wording. When I saw "inherently" I read that as you saying there is factual, statistical, scientific reasons that the 6.5 has better ballistic POTENTIAL than a larger .277 caliber. It's a pet peeve of mine when people claim certain calibers have special qualities that ignore the obvious linear relationship between diameter and potential BC.</p><p></p><p>Thanks for pointing to the Litz article I had not read that in years. It was good to revisit even if the information is a little outdated regarding the heaviest bullets offered. In his critique of the 30 cal bullets he doesn't say anything about them having inherently lower bcs. The problems are many. From the heavy sierras are running the same nose and boat tail as the 155s and therefore have a crazy long bearing surface that makes a mess of things. The assortment at that time actually being to light. To how much recoil is generated if you run true heavy 30s at high velocity.</p><p></p><p>If I had the time and inclination I would put together a real world graph of what is realistically possible, but here is the short hand.</p><p></p><p>Caliber, heavy commercially avail bullet weight, G7 BC</p><p></p><p>.223 90gr .274</p><p>.243 115gr .291</p><p>.257 131gr .340</p><p>.264 156gr .347</p><p>.277 170gr .339</p><p>.284 195gr .387</p><p>.308 245gr .413</p><p>.338 300gr .421 </p><p>.375 407gr .532</p><p>50 750gr 1.21 G1 bc is all that avail.</p><p></p><p>I can hear people saying that the .277 is the weakling here. I would say if you look at the increase in bullet diameter and compare it to the increase in bullet weight, you can see that the .277 is still a little underweight even at 170gr in this elite class. Regardless, the math/science is clear. As diameter goes up BC potential does too. Nothing mystical happens at any specific caliber to disprove this. People said the same thing about the .257 until a few years ago when it got a little love and now it falls right in line with other top tier performers.</p></blockquote><p></p>
[QUOTE="TX Badger, post: 1954323, member: 95235"] If you are only considering what is commonly avail., you are correct. If you hamstring the .277 with a 1:10 then yes. If you want to compare a sammi spec chamber from the 30s to something more modern then yes, a long heavy for caliber bullet can be an issue. Maybe we are just differing on the wording. When I saw "inherently" I read that as you saying there is factual, statistical, scientific reasons that the 6.5 has better ballistic POTENTIAL than a larger .277 caliber. It's a pet peeve of mine when people claim certain calibers have special qualities that ignore the obvious linear relationship between diameter and potential BC. Thanks for pointing to the Litz article I had not read that in years. It was good to revisit even if the information is a little outdated regarding the heaviest bullets offered. In his critique of the 30 cal bullets he doesn't say anything about them having inherently lower bcs. The problems are many. From the heavy sierras are running the same nose and boat tail as the 155s and therefore have a crazy long bearing surface that makes a mess of things. The assortment at that time actually being to light. To how much recoil is generated if you run true heavy 30s at high velocity. If I had the time and inclination I would put together a real world graph of what is realistically possible, but here is the short hand. Caliber, heavy commercially avail bullet weight, G7 BC .223 90gr .274 .243 115gr .291 .257 131gr .340 .264 156gr .347 .277 170gr .339 .284 195gr .387 .308 245gr .413 .338 300gr .421 .375 407gr .532 50 750gr 1.21 G1 bc is all that avail. I can hear people saying that the .277 is the weakling here. I would say if you look at the increase in bullet diameter and compare it to the increase in bullet weight, you can see that the .277 is still a little underweight even at 170gr in this elite class. Regardless, the math/science is clear. As diameter goes up BC potential does too. Nothing mystical happens at any specific caliber to disprove this. People said the same thing about the .257 until a few years ago when it got a little love and now it falls right in line with other top tier performers. [/QUOTE]
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So Will the .270 Win Overtake the CM's and PRC's?
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