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Old 09-03-2011, 10:39 PM
bernieb90 bernieb90 is offline
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Quote:
Originally Posted by killshot44 View Post
You mean this one?

Get the 1/9 twist unless you're only going to shoot 77s. As others have mentioned, an 8 twist is pretty much ideal for the whole spectrum of weights. A 1/9 will actually shoot 69s well and the "green" area above for a 1/8 should be much broader.
Huh? The original M16 had a 1:14 twist rate. This was found to be inadequate for stabilizing M193 (55Gr bullet) in Arctic conditions, and the twist rate was changed to 1:12. Then M855 was adopted the new M856 Tracer required a much faster twist to stabilize it. In fact it was closer to 1:6.5. 1:7 however was chosen as a compromise.

1:9 works fine for most users. In fact there are a host of new sub 70gr loads right now that provide excelent barrier-blind performance, and work great in a 1:9 barrels. If you want to shoot heavy 75/77gr OTMs at long range then 1:8 or 1:7 makes sense. Also heavy OTMs provide the best terminal performance against unobtructed "soft" targets so many people use them for tactical applications.

The reason most high end ARs come with 1:7 twists is that many of these companies also have military contracts or cater to military users as well as civilians. Making barrels with multiple twists means additional tooling, and costs without much benefit. BCM, LMT, DD, Noveske all use 1:7 twist exclusively because of this.
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