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Posted: 7/28/2008 10:24:30 PM EDT
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I was wondering what's consider the optimal velocity for a .223 round? As most of you know there's a trade off between velocity and accuracy. I always heard there's a "magic" number for this.. but never had a idea what the velocity would be.. I suppose that would be subjective to the equipment. Rifle: AR, 16" barrel, 1/8 Twist, Wylde Chamber Powder: Varget Bullets plan to use: Hornady 60gr VMAX (Flat Base) Nosler 69gr HPBT Sierra 69gr HPBT I was thinking that 3000-3100 for the velocity would be good. Of course I know every rifle has it's favorite setup.. but just wanted a target starting point. Thanks. |
| "3000-3100" fps for 16" would be a hot load. Even for 60gr bullet. Accuracy will usually peak in 2 different level. Sweet spot on lower FPS and another sweet spot on higher FPS. Might have to watch for pressure signs when searching for the high velocity/accuracy combo. And stay below max loads. Too many variables to get a exact load from start. You can try listed loads on sticky and work from there. HTH |
| I don't think 3000 is realistic in a 16" barrel. My guess would be 2750 Max with the 69 grain bullets and 2800 with the 60gr and approx. 2650 fps with 77bthp match loads. I may be wrong but I'd think the above would be max loads. Your results may differ and I'm sure you'll get some other reloaders results. |
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You need to workup a load for your chamber/barrel. What is the perfect accuracy/velocity node for MY rifle will probably not be equal for YOUR rifle. Additionally what MY requirements are may not be the same. Since I have a 380 yard range right now I don't need to burn up my barrel with peak velocity. I can use the lower velocity node and still have acceptable elevation for adjustment. |
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There's no such thing as an "optimal velocity". Every rifle is different, ambient conditions are different, and components are different. Likewise, there's no such thing as a strict trade between velocity and accuracy. The gun, shooter, and load are either accurate, or they aren't. The speed of the bullet is whatever falls out, but it's important to know if we're shooting at long distances so we can get the first shot on paper, and then refine the sight settings to account for the unique combination. One shooter's optimum might be another shooter's unusable dog. If all you're going after is speed, I'm probably not interested, particularly if the load shoots a 6 inch group at 100 yards. Ryo, You should have second thoughts about going after those speeds with the 69 gr bullets. Those are very high speeds and you can bet the loads will be way over pressure to get there. Even speeds in the 2800 to 2850 fps range will be sporting. |
QL also states do not use this load as well. Optimal velocity would have to do with terminal ballistics, best framentation/wound channel. |
| Hmm.. strange, based in my manual, the loads I have been building up, and have tried firing (60gr) were estimated to be a little under 3000. I plan to chrono my loads in a couple of weeks to see if the manual matches reality. I have a few rounds I already worked up from min to under max to see which load works the best. Don't know if I can determine what's best for my AR, with my small samples (50 rds each), but I'll see. |
This is the first time i have read somenone state getting accuracy in 2 different loads with the same components. I am curious being new to reloading .223 and believe i have found ( or come close ) similiar results using H335 and 55FMJ. Anybody/everybody find this to be true? For just practicing within 200yds would you use the lower FPS to save powder? |
Yes, this is common. The charge weights I've found weren't very close together. |
Same results here, just thought i was shooting better one day while working this load up . |
This is the heart of your misconception. There are several trade offs between accuracy and velocity. Each gun will have a set of velocities where a bullet is very accurate separated by spans of velocities where the bullet is not so accurate. Some call these effects "barrel harmonics" and you can google "Optimal Barrel Time", "Audette Ladder", and "Optimal Charge Weight" for a complete run down. The optimal velocity varies with powder while the optimal barrel time does not!?!!? 
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60gr and 68/9gr. HPBT bullets are completely different animals, as are 75gr and 77gr. projectiles. They have a longer bearing surface, a longer length, and require a smaller powder charge. 27-2800 FPS is all you can expect from a 16" barrel. A 26" barrel will get you closer to 3000 FPS. |
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