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Posted: 1/17/2011 7:33:27 AM EDT
[#1]
Quoted:
Molon, why is the 1:7 the choice of all the "top tier" makers as well as the military, over the 1:9? not Molon, but I believe it has to do with the length of the Tracer rounds. From what I've read in ARFCOM when the twist rate question comes up, it seems that the 5.56 tracer rounds are longer than M855 or M193 and take a faster twist rate to stabilize. I assume the "top tier" manufacturers do so because a 1:7 twist is specified in the TDP supplied to Colt and FN by the US DOD. |
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Posted: 1/17/2011 8:40:00 AM EDT
[#2]
Quoted:
Quoted:
Molon, why is the 1:7 the choice of all the "top tier" makers as well as the military, over the 1:9? not Molon, but I believe it has to do with the length of the Tracer rounds. From what I've read in ARFCOM when the twist rate question comes up, it seems that the 5.56 tracer rounds are longer than M855 or M193 and take a faster twist rate to stabilize. I assume the "top tier" manufacturers do so because a 1:7 twist is specified in the TDP supplied to Colt and FN by the US DOD. So 1:9 will stabilize heavier rds such as 75 and 77 gr just as well? I've always thought that 1:9 would not. Another BS buster? There are no other benefits to 1:7? |
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Posted: 1/17/2011 9:19:52 AM EDT
[#3]
Excellent thread as usual, Molon! Thank you for all your highly informative threads over the years.
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Posted: 1/17/2011 10:06:15 AM EDT
[#4]
There seems to be no set answer to that other than "try it with YOUR barrel."
Edited because Zhukov has posted better info than I could. |
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Posted: 1/17/2011 10:35:04 AM EDT
[#5]
Quoted: So 1:9 will stabilize heavier rds such as 75 and 77 gr just as well? I've always thought that 1:9 would not. Another BS buster? There are no other benefits to 1:7? Incorrect. 1:9's will MARGINALLY stabilize the heavy rounds. 75gr is usually OK, 77 is pushing it. Even if it does stabilize, it's on the borderline and accuracy is quite a bit worse. Molon did a test of that in one of his posts. Look through the FAQ under "Molon's collected posts". Click on that and read through the topics. One of them will have the post I'm referencing. |
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Posted: 1/17/2011 1:32:19 PM EDT
[#6]
thank you for the correction Zhukov. I missed the 77grain part entirely
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