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Discussion Starter · #1 ·
I'm researching AR15's but I guess this info applies to any rifling. What are the advantages and disadvantages to going with faster twist rates? I noticed some AR15s come with 1:7 while 1:9 seems to be more common. I read the 1:7 will wear faster but was designed to stablize the tracer round (longer bullet). Any other differences?
 

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Discussion Starter · #2 ·
Other than the additional wear, any reason not to go with the faster twist?
 

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Discussion Starter · #3 ·
Thanks for the info. Actually I have my eyes on a Colt LE6920. Now, if I cannot obtain one by the time I get the money I will likely go with a M4 Bushmaster or RRA.
 

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I do like the 6920, my 6400c looks "almost" like it (no bayo lug). You may do some research on "residual value" of the RR and BM compared to Colt. I think the Colts hold their value better.

I personally have not found any difference in the 1/9 and 1/7, they both tend to do the same thing for me. Maybe if shot at full auto all the time, but that won't happen, unfortunately...

Check out this info from Bushmaster if you haven't read it, there is another really long explaination about twists/wear. I couldn't find the link, but you may check the "tacked" areas over at arfcom.
 

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Discussion Starter · #6 ·
They are supposed to have a little better quality control. They also seem to have better resale. The research I have done so far says that Colt is marginally to no better than other top line manufactures.

Really it just comes down to I'd rather have one. When someone mentions AR15/M16 I first think of Colt. I also like the LEO markings of the LE6920. If the Colt is not available when I'm ready I will happily get RRA or Bushmaster as a sub. The money I save will go toward magazines and ammo.

Don't get me wrong, I still hope for the Colt. I just refust to pay $1500 for one.
 

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Discussion Starter · #7 ·
kevin_m4 said:
I do like the 6920, my 6400c looks "almost" like it (no bayo lug). You may do some research on "residual value" of the RR and BM compared to Colt. I think the Colts hold their value better.

I personally have not found any difference in the 1/9 and 1/7, they both tend to do the same thing for me. Maybe if shot at full auto all the time, but that won't happen, unfortunately...

Check out this info from Bushmaster if you haven't read it, there is another really long explaination about twists/wear. I couldn't find the link, but you may check the "tacked" areas over at arfcom.
Thanks for the link.
 

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I like the 1X9 twist. it shoots real good with the cheap FMJ 55 & 62 gr bullets
 

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I honestly believe that the best all around twist for a SA AR rifle is the 1x9.
It will give you the best performance over a wider variety of bullet weights than any other twist rate.
 

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Hopefully I can add something helpful to this. In reference to the M16/AR15 rifles the twist rates changed when the ammunition changed. The M16A1 was a 1:12 twist for use with the 55gr ammunition that was standard issue at the time. The smaller lighter bullet needs a slower rate to stabilize itself in flight. When the M16A2 was developed it was changed to a 1:9 twist for use with the 62 grn SS109 cartridge. A bigger bullet needs a faster twist rate to stabilize. My only AR15 is a DPMS Sweet 16 Bull barrel with a 1:8 twist. I shoot only hand loaded 75 grn match hollow points through and you can tell the difference however slight.

I do mostly bolt gun work and the knowing the type and size of bullets that you plan to use is the most important part of choosing both a barrel and a twist rate. I currently shoot 50 grn bullets from my 22-250 Ack Imp bench rifle with a twist rate of 1:14. Just remember the bigger the bullet the faster the twist rate.

As far as an AR goes I think I would just settle for the 1:9. It's pretty versatile and like WC 846 stated above........ you will probably shoot both rounds equally well. I would avoid the 1:7 though. That guy is made for serious long range shooters. In fact most of the time they have to load their rifles one round at a time. The big bullets are too big to fit into a standard magazine.

Did that help at all?
 

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Discussion Starter · #11 ·
It looks like the 1:9 is the popular choice. I would be shooting mostly 55gr (M193) & 62gr (M855) ammo. The 1:7 caught my eye because

A: it is the twist rate used in the Colt LE6920
B: the military M4 are using this twist (I think)


Which of these would you prefer and why?
Colt 6920
Colt 6721
 

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If I absolutely had to buy a Colt (which hopefully never happens) I would go with the 6721. They seem to be about the same except for the twist rate.
 
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