.300aac upper for Larue obr?


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Collector0311
March 1, 2012, 11:28 AM
Want to pick up a Larue obr (5.56) and a .300aac upper. Any tips, or personal experience from any of you gentleman as to which manufacturer of .300aac uppers would best mate to the Larue would be much appreciated. Also not opposed to anybody arguing a better host rifle for my purposes. Basically want a billet upper and lower that I can swap easily between these two calibers. Thanks in advance. -Brandon

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rjrivero
March 1, 2012, 12:16 PM
Buy a second Larue upper and put in a 300 AAC Blackout barrel. That way it would match PERFECTLY. There isn't anything "magic" about one upper or another.

AAC announced recently that they'll be changing their barrels to 1:7 twist to better stabilize new(er) longer subsonic bullets. I don't think their 1:7's are available just yet. Most everyone else is using 1:8.

68wj
March 1, 2012, 12:24 PM
Buy a second Larue upper and put in a 300 AAC Blackout barrel. That way it would match PERFECTLY. There isn't anything "magic" about one upper or another.

AAC announced recently that they'll be changing their barrels to 1:7 twist to better stabilize new(er) longer subsonic bullets. I don't think their 1:7's are available just yet. Most everyone else is using 1:8.
Sounds pretty reasonable, especially if another billet will be used anyway. Even AAC is saying the difference between 1/7 and 1/8 isn't worth worrying about. It sounds more like marketing to me, unless you plan to focus on subsonic use and are concerned.

Z-Michigan
March 1, 2012, 03:29 PM
Even AAC is saying the difference between 1/7 and 1/8 isn't worth worrying about. It sounds more like marketing to me, unless you plan to focus on subsonic use and are concerned.

What I've read is that it will likely only matter if you want to use >240gr match low drag style bullets at subsonic speeds. Even then, some 1:8 barrels will stabilize them, but some won't. Some of the 240+ gr bullets are a different profile (more rounded/straight sided) and work just fine in a 1:8, consistently. For most people it isn't worth getting excited about. The more common subsonic load is a 220gr SMK and that works fine in a 1:8.

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