Gibbs Posted August 27, 2014 Report Share Posted August 27, 2014 YEP!! Excellent groups! Quote Link to comment Share on other sites More sharing options...
j.peace Posted August 28, 2014 Report Share Posted August 28, 2014 Very nice shooting!! Quote Link to comment Share on other sites More sharing options...
Pegasus Posted September 5, 2014 Report Share Posted September 5, 2014 Just so you know. 1:11.25 is a fine twist for the .308 Win pushing bullets as heavy as 180 or 190 grs. I've pushed 200SMKs to 1000 yards in one of my F-TR rifles which has that specific twist. The weight of the bullet is not the main determining factor in selecting the twist rate; bullet length is. Most .308 rifles are 1:12 twist but as mentioned before, there are 1:11.25, 1:11 and 1:10 twists in many 308ARs. If your twist is too slow, the bullet will be unstable when it leaves the bore and will start tumbling and you can see this a oblong holes or keyholes on the target, if it even gets there. If your twist is too fast, the bullet could spontaneously disintegrate 50-70 yards downrange, but while I have seen lots of 6mm bullets undergo the sudden transformation from bullet to white puff cylinder downrange, I have never seen or heard of a regular .30 caliber bullet doing that. It is generally accepted that spinning a bullet fast can help accuracy, but there are many caveats to that statement. Let's just say that as long as you use nothing heavier than say 190gr bullets, you will be well served with you 1:11.25 twisted barrel. Quote Link to comment Share on other sites More sharing options...
D.R.D. Posted September 5, 2014 Report Share Posted September 5, 2014 Can you elaborate and give examples (measurements) of bullet lengths that you feel work best with certain twists then? Quote Link to comment Share on other sites More sharing options...
edgecrusher Posted September 5, 2014 Report Share Posted September 5, 2014 You'll will run into oal issues with the larger projo's, I willing to bet the 190's he's stating won't even load into a magazine Quote Link to comment Share on other sites More sharing options...
survivalshop Posted September 5, 2014 Report Share Posted September 5, 2014 (edited) That may be a long answer ,there are so many bullet types out there & pretty much weight will have something to do with bullet configuration , not to mention bullet composition. ( like solid copper or what ever ) The way I look at it , you have to try multiple manufacturers , bullet types & weights , to see what shoots the best , there is no one magic bullet combo that will work in all barrels twist rates. Edited September 5, 2014 by survivalshop Quote Link to comment Share on other sites More sharing options...
edgecrusher Posted September 5, 2014 Report Share Posted September 5, 2014 The way I look at it , you have to try multiple manufacturers , bullet types & weights , to see what shoots the best , there is no one magic bullet combo that will work in all barrels twist rates. Yup, the man is wise! Quote Link to comment Share on other sites More sharing options...
Pegasus Posted September 6, 2014 Report Share Posted September 6, 2014 If you limit yourself to anything that you can load to mag length in a .308AR, a 1:12 twist will be just fine and a 1:11.25 or 1:11 (my personal favorite for long range) will be even better. My Ar-10(T) has a 1:10 twist so I'm not worried about loading anything in there. However, that said, the beauty of the AR platform is that you can single load if you want. If you ever compete in XTC or NRA HP, you have to single load at anything greater than 300 yards. The AR platform is amazingly flexible and it will allow you to single load with no problems. I have a Bobsled for one of my AR-15s (NM) and I also have a Bobsled for my AR-10(T). If ever I get the urge to try a really long bullet like some of the VLDs that I use for F-TR in my AR-10, I can. That's flexibility. Did I mention that I love the AR platform? Now, in answer to the question which twists work best with which bullets, my thinking is that the question is reverse of what it should be. What you want to know is which bullets lengths or weights will not work for specific twists. Then you can experiment with what remains. So, a 1:10 will not like bullets that are heavier than 230 grains. (Notice that I don't use length here because nobody sells bullets by lengths. I invite you to check out JBM's database of bullet lengths. For a 1:11 or 1:11.25 twist anything much past 200gr will be iffy, but do remember that plastic tips don't count. For a 1:12 twist, anything heavier than a 175/180gr gets iffy. You can visit the web site of various bulletmakers to see what their recommendations are. I usually subtract one more inch from their recommended twists. So if a site suggest a 1:12 twist for their bullet, I use 1:11. JBM has a stability calculator, and I would recommend that the minimum stability you want to have is 1.5 for your bullet/twist/velocity combo. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted September 6, 2014 Report Share Posted September 6, 2014 (edited) Just so you know. The weight of the bullet is not the main determining factor in selecting the twist rate; bullet length is. Thanks for that enlightening tidbit of information, Pegasus. Please answer this question for me though - if you're constricted to a certain diameter (say .308") then a fucking HEAVIER bullet would be a LONGER bullet, would it not?! Construction being similar, and not talking about Tungsten here. A full metal jacket boat tail bullet that's 150gr is SHORTER than a full metal jacket boat tail bullet that is 180gr - in .308" bullet. Tell me that's wrong information. You're another F-Class jackass that has showed up here, and you want to school everybody on what you think you know. Why don't you shut your mouth for a minute and try to learn something here? I can answer why you probably will not do that - you're already smarter than the rest of the class. If that's the route that you want to take, then just take your ass to the door. Edited September 6, 2014 by 98Z5V Quote Link to comment Share on other sites More sharing options...
Pegasus Posted September 6, 2014 Report Share Posted September 6, 2014 If you are talking about the exact same style and composition for the bullets, then you are correct. But that's a limited view of what is available and the question was weights and twists; it didn't say anything one specific style. Survivalshop even mentioned there are many bullet types and weights. For example, if you compare a Sierra 175MK, arguably one of the best mag-length bullets, with a length of 1.240 inches to a Berger 155 Hybrid, which has a length of 1.280 inches, you can see that the heavier bullet is actually shorter than the lighter bullet and they are both BTHP, jacketed lead core bullets. You can be quite sure that even though the 155 only weighs 5 grains more than a 150gr FMJ-BT, it will require a faster twist to stabilize. And please, do not tell me what to do. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted September 7, 2014 Report Share Posted September 7, 2014 And please, do not tell me what to do. Too late - go fuk yourself, too. You did it to yourself here, buddy - and it's rightly deserved. I just wish I could have gotten home sooner, before you got the boot. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted September 7, 2014 Report Share Posted September 7, 2014 If you are talking about the exact same style and composition for the bullets,... Reading Comprehension kicks your A$S, doesn't it? I clearly - CLEARLY - stated this in my post, then you responded to it. Construction being similar, and not talking about Tungsten here. A full metal jacket boat tail bullet that's 150gr is SHORTER than a full metal jacket boat tail bullet that is 180gr - in .308" bullet. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted September 7, 2014 Report Share Posted September 7, 2014 Peggy Sue, just so you know - you HELPED me achieve a goal that I've been looking for now for a long time. Double Digit Warning Points. Thanks to the interaction with you, I'm now at 10. <thumbsup> Quote Link to comment Share on other sites More sharing options...
ChaseFan9 Posted March 19, 2015 Report Share Posted March 19, 2015 (edited) Wow, ANYWAYS.... I think this might be able to help you out: http://www.armalite.com/images/Tech%20Notes%5C2015%5CTECH%20NOTE%20110.pdf And remember there's always that X factor. Some barrels just love to run certain rounds. Edit:also just realized how old this post was my bad y'all Edited March 19, 2015 by ChaseFan9 Quote Link to comment Share on other sites More sharing options...
Sisco Posted March 20, 2015 Report Share Posted March 20, 2015 Thanks ChaseFan9, actually it was very pertinent to the thread, so why not? Quote Link to comment Share on other sites More sharing options...
ChaseFan9 Posted March 20, 2015 Report Share Posted March 20, 2015 Thanks, I do what I can :) Quote Link to comment Share on other sites More sharing options...
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