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My first AR build 2012...


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Old 01-01-2012, 01:09 PM   #11
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ScottA, a little thread drift here, but my Dad was part of the TWA Team in Kansas City that restored that old Connie into flying condition. He was with TWA for 55 years.
Your dad did one heck of a job. It is such a beautiful bird. I'm hoping to get a chance to tour it sometime in the near future. Maybe they'll bring it up to Oshkosh soon.
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Old 01-01-2012, 02:44 PM   #12
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i'll give a very basic explanation of the twist ratios. The three best suited for AR15's are 1:7, 1;8, and 1:9. For some reason the 1:8 twist doesn't show much difference in accuracy from the 1:7 twist plus it's kind of a rare, funky twist so a bit harder to find a good selection of barrels offering it. The 1:9 twist has shown superior due to slighter smaller twist. Twist rates, as forementioned, are largely suited for the heaviness of the ammo you're shooting which. If the twist ratio is too high, the bullet becomes unstable due to the low weight. If the revolutions are too low, you risk not finding the full potential of the shot. 1:7 twists are the most common to find in AR15's (even most militaries use 1:7) but on standard 16 inch barrels it's found that the twist is still trumped by the 1:9 twist. Now granted you won't be able to tell a lick of difference for anywhere up close but when you push 'er to the limits on range you'll definately be able to tell. Like i said, the grains you're using makes a difference and this 1:7-1:9 twists are best suited fpr 55-62 grains which is what you're wanting to use. i was wanting to stray away from using this much explanation earlier which is why i simply said 1:7 is good, 1:9 is best. Either way you can't go wrong! And as for the 16 inch barrels, they're the most common as well as the most plausible. 16 inch barrels are *usually* very lightweight and still do great on distance/accuracy. Barrels can get much larger but then you're taking off from the original beauty of the AR15. The are made to be compact, lightweight rifles and you're doing with barrels larger than 16 inch is add weight and sacrificing maneuvarability. So again, you're off to a good start!
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Old 01-01-2012, 06:00 PM   #13
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Secondhand you are off on your explanation of twist rate.

1:8 is not hard to find, it is actually quite common. I have no personal experience w/ 1:8 but the reports are that the 1:8 wylde as is common place is more accurate than 1:7 and 1:9.

1:9 has not been shown to be superior. In fact I have never heard of anyone who uses an AR for any hard use say they prefer 1:9 over 1:7. In fact most would laugh at the thought.

Twist is subject to the length of the round more than weight.

1:7 is suitable for weights much higher than 62 grains. Many guys use 77 grain and higher for competitive/target shooting out of 1:7.
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Old 01-01-2012, 06:14 PM   #14
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I think many people assume that twist rates determine the ultimate accuracy of barrel.

Twist rates are merely a single factor. Getting a suitable rate for your intended use is important, but should not be considered an indication of the quality of a barrel.
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Old 01-01-2012, 06:22 PM   #15
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I think many people assume that twist rates determine the ultimate accuracy of barrel.

Twist rates are merely a single factor. Getting a suitable rate for your intended use is important, but should not be considered an indication of the quality of a barrel.
The combo of twist rate, type of rifling, and chamber along w/ overall quality.
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Old 01-01-2012, 07:21 PM   #16
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QFive, it's good that you're thinking this thing out. You sound like the type who will do a great job rolling your own. Most people start picking up the knowledge after their purchase!

As far as twist rate you have to figure out now what bullet weights/lengths you'll normally use. If you'll normally go with 62gr and under, maybe even under 55gr, well 1:9 makes sense. If you'll be shooting 55 and up, then consider 1:7. As you can see there is overlap and it's right in the sweet spot of 55-62. I'd say lean toward 1:7 in a quality barrel and really look at lightweights. Later you may want to build a varmint upper...and a slower twist in a heavier barrel.
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Old 01-01-2012, 07:48 PM   #17
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The combo of twist rate, type of rifling, and chamber along w/ overall quality.
Ill add how the crown is cut and uniformity of construction, but ya lots of stuff that can't be seen thru casual inspection. Its best to go with someone with a good rep.
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Old 01-01-2012, 08:21 PM   #18
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First off thank you all for the replies. I can see there are a few schools of thought on barrel twist. I do not plan to shoot under 55grain. Also I don't really plan to shoot larger than 62 grain. It appears most believe 1:7 is the best route and there isn't much significance vs a 1:9 twist. I understand there are other aspects in regards to barrel quality and accuracy. Also I understand ammo choice and FFR affect accuracy as well.

Now this leads to my questions in regards to building an upper or buying an upper. Also any recommendations on quality brands and what to stay away from are welcome. In regards to quality if I am correct I believe PSA uses FN Barrels. Ive heard good things. I know there are other brands that are good. Any in particular that stand above but are still priced well?

I am curious as to why the recommendation use a light weight barrel profile vs medium etc. I don't plan on doing mag dumps but after shooting some pencil and other thin barrels they heated up rather quickly and began to drift. Any input on this? I am assuming this is all barrel manufacturing and brand dependent such HF vs CMV vs SS barrels. I am thinking HF chrome lined but any suggestions are welcome. Ive had people say HF isn't necessity unless really abusing etc.


Again thanks for the help so far I look forward to any tips/info you want to throw my way.
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Old 01-01-2012, 09:44 PM   #19
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Well the standard government profiles are as thin as the pencil barrel under the handguards, then thickens from there to the muzzle. Doesn't make much sense so why not just get the lightweight barrel in the first place and save 5 oz or more. You'd be amazed how maneuverable this makes the rifle. I haven't noticed POI drift due to heat up but I don't dump magazines either. My Daniel Defense LW midlength barrel is CHF so that may help in that regard but I agree with you that hammer forging usually is not necessary.

Nothing wrong with building up a stripped upper but there are so many great factory built uppers configured just about anyway you want (and test fired). You don't save much or anything building an upper so most of us just build the lower and shop around for the right upper.
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Old 01-01-2012, 11:54 PM   #20
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I've kinda got the same situation going on. I want to build a 14.5 inch lightweight carbine, but almost all the barrels I've found or reasonably priced uppers have a 1:7 twist. Since this rifle will be used for general shooting it would not be unrealistic for me to find a good price on 55 gr ammo from my LGS. I'm concerned that the twist rate my be to fast for the 55 gr ammo. I'd hate to limit myself to 62 or heavier. I rarely shoot over 100 yds so this may not be an issue.

I've read the sticky and discussions on this and other forums, but know one has said whether you lose alot of accuracy or not. Can someone chime in about 55 gr ammo in a 1:7 twist at short range (under 100 yds)
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