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Old 11-02-2012, 12:54 PM   #1
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Default 20in barrel

What are the the benefits of a 20in barrel. Considering building an ar in the m110 style.

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Old 11-02-2012, 01:05 PM   #2
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More muzzle velocity. What kinda twist you looking at?

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Old 11-02-2012, 01:58 PM   #3
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The upper I am looking at is a bcm. It has 1/7.

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Old 11-02-2012, 02:23 PM   #4
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That should pretty much shoot whatever ya want, haha. If you're looking at the SASS/ DMR/ SPR rifles check out a MK12 barrel by DPMS. They're really nice and MidwayUSA has them on sale.

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Old 11-02-2012, 02:38 PM   #5
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I wouldn't shoot 36gr and 40 gr bullets with a 1/7 twist. 55 gr and up only.

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Old 11-02-2012, 02:49 PM   #6
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Chck out ar15 performance, and Black Hole Weaponry barrels for great budget minded precision oriented barrels.

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Old 11-02-2012, 02:58 PM   #7
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I would stay with 55 and 62. That's what I shoot out if my PSA 1/7. I don't know if im ready to get that in depth with a build. That's why I was looking at the barreled uppers. This is my second ar. First was a kit plus a stripped lower. Think a complete build might be out of my scope of practice still. The bcm is a nice upper. Has a midwest industries ss 15 gen 2 ff handguard on it

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Old 11-02-2012, 11:01 PM   #8
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Im trying to plan this all out. I want to buy a lower now(just in case), but Im not sure what to do. Buy a stripped lower and parts kit later or buy a lower kit with with lpk/stock. I also can't decide which stock to go with. I know i dont like the fixed stocks. What is your recommendations.

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Old 11-03-2012, 12:09 AM   #9
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http://www.firearmstalk.com/forums/f20/ar15-primer-beginners-guide-59600/



For longer distances you want your bullet to be going as fast as possible so you can be as accurate as possible. Also increasing muzzle velocity increases the energy the bullet has to transfer to and incapacitate the target. Also for long distance shooting you want your bullet to be as heavy as possible with the highest BC (ballistic coefficient) so that it is resistant to changes in trajectory by wind. All things being equal, a heavier bullet loses less energy over a given distance than a comparable lighter weight bullet.

Your average M4 style 16” carbine is good for short and intermediate distances, (0-400 yards). At longer distances 300+ yards and up), the common 55 grain (gr) full metal jacket (FMJ) becomes very susceptible to shifts in point of impact due its light weight. For longer distances (400+ yards) you should consider a heavier and longer projectile, like a 69 gr, 77gr, 80 gr etc. For those bullets, a faster twist rate (1x8 1x9) is needed to stabilize the projectile. Long distance shooting is usually not for your average first time buyer. There are a lot of factors and decisions that must be made for long distance precision builds that are best left for more experienced shooters.

If you opt for a 18” or 20” barrel, you gain muzzle velocity and sight radius while trading off weight and handling. One added benefit of rifle lengths is that the gas system for rifles is noticeably smoother than shorter systems. The powder has time to burn evenly and completely. The gas produced has a lot more room to expand, and by the time it gets to the gas port it can cycle the BCG much more smoothly and evenly.
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Old 11-03-2012, 02:10 AM   #10
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Tikki, ive read youre primer a few times. I thank you for it great piece. You have to understand that im not a good enough shooter to worry about effects of a bullet out at any distance lol. Im really looking just to build another ar and I really like the look of the SASS or M110 and I want one to dedicate a rifle scope on. PSA has a 16in with the MI SS12G2 handguard and BCM has the 20" with the MI SS15G2. I thought the longer rifle fits the rifle scope look better.

I know a lot of people say that they dont like it when people buy/build guns that are "clones" and what not, but I like to shoot and have what I think looks good. I guess first of all i really need to decide on a lower option.

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