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delliottg
Site Supporter
Location: Duvall Joined: Thu Mar 17, 2011 Posts: 4599
Real Name: David
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I'm looking at building a rifle with one of my new lowers. PSA has pretty much exactly what I want on sale today: PSA 16" MID-LENGTH 5.56 NATO 1/7 NITRIDE MOE DISSIPATOR RIFLE KIT, OLIVE DRAB GREENMy question is this. The 1:7 twist rate is designed to stabilize heavier bullets like up to about 80 grains. I've read conflicting viewpoints on how well it'll stabilize 55 grain plinking ammo (which is what I've got lots of). Some say you want a slower twist rate so you don't over-stabilize the bullet, while others say it's difficult to over-stabilize and the US Military has settled on the 1:7 twist rate barrel so why shouldn't you? Thoughts?
_________________David Unique Treen
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Thu Apr 27, 2017 2:31 pm |
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edogg
Site Supporter
Location: Central FL Joined: Sun Apr 7, 2013 Posts: 3207
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My ARs are 1:7 because that's a good all around twist rate. It stabilizes both 55gr and heavier 62/77gr well.
A slower rate might make for better 55gr accuracy at the sacrifice of 62gr accuracy.
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Thu Apr 27, 2017 2:52 pm |
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Acpguy
Site Supporter
Location: Lacey Joined: Wed Jul 11, 2012 Posts: 920
Real Name: Deke
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My 20' black hole barrel will put up sub 1/2' groups all day long no with 70gr -80gr it loves the 75-77gr. But barely puts up 1moa with the 62gr and the 55gr shoots minute of paper target lol (somewhere around 14'moa).
Every rifle is diff but this is my experience.
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Thu Apr 27, 2017 4:27 pm |
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ryanl4570
Location: Puyallup/South Hill Joined: Sun Sep 21, 2014 Posts: 70
Real Name: Ryan
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I have a 1/7 nitride mid Length set up from PSA and it shoots 55-68 just fine. Very reliable with better than average accuracy.
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Thu Apr 27, 2017 4:58 pm |
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golddigger14s
Site Supporter
Location: Faxon, OK Joined: Sat Mar 19, 2011 Posts: 17806
Real Name: Chuck
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Go in the middle with a 1:8 twist?
_________________ "The beauty of the Second Amendment is that it will not be needed until they try to take it." Thomas Jefferson "Evil often triumphs, but never conquers." Joseph Roux
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Thu Apr 27, 2017 5:05 pm |
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delliottg
Site Supporter
Location: Duvall Joined: Thu Mar 17, 2011 Posts: 4599
Real Name: David
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golddigger14s wrote: Go in the middle with a 1:8 twist? Well, the sale is for a package deal with the 1:7 barrel.
_________________David Unique Treen
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Thu Apr 27, 2017 5:07 pm |
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OhShoot!
Site Supporter
Location: Bellingham Canada Joined: Thu Jan 3, 2013 Posts: 4998
Real Name: Josheewa
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I am in the 1:8 club
_________________ It must be frustrating always being the smartest person in the room.-Jagerbomber35
Divided we fall.
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Thu Apr 27, 2017 5:18 pm |
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DJ_Mack
Location: Everett Joined: Mon Jun 29, 2015 Posts: 157
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My 1:9 chrome lined m&p barrel is my most accurate. But all I shoot is 55gr. I have a 1:8 & a 1:7.
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Thu Apr 27, 2017 5:45 pm |
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delliottg
Site Supporter
Location: Duvall Joined: Thu Mar 17, 2011 Posts: 4599
Real Name: David
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Crap, or not. I waited too long and now it's out of stock. Oh well, PSA cycles through their sales fast enough, it'll come back around.
_________________David Unique Treen
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Thu Apr 27, 2017 6:15 pm |
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Soldier_Citizen
Site Supporter
Location: south 'merca Joined: Wed Jul 25, 2012 Posts: 9736
Real Name: Mike
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For plinking and range fun it's fine. I get shitty groups out of my 1/7 with 55 grain. Decent with 62 grain(1"ish) groups, and she's a tac driver with 69-77 grain. I'm rolling 75gr hpbt's and have been very satisfied
_________________"No Quarter, No Mercy" mash_man wrote: #gangbangerlivesmatter
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Thu Apr 27, 2017 6:17 pm |
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edogg
Site Supporter
Location: Central FL Joined: Sun Apr 7, 2013 Posts: 3207
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Acpguy wrote: My 20' black hole barrel will put up sub 1/2' groups all day long no with 70gr -80gr it loves the 75-77gr. But barely puts up 1moa with the 62gr and the 55gr shoots minute of paper target lol (somewhere around 14'moa).
Every rifle is diff but this is my experience. Do you mount your 20' black hole barrel to a wheeled or tracked vehicle? ;) Sent from my iPhone using Tapatalk
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Thu Apr 27, 2017 7:00 pm |
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hkcavalier
Site Supporter
Location: NE WA Joined: Tue Oct 18, 2011 Posts: 5470
Real Name: The Dude
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This story has been told a lot...
1:7 is the military spec b/c of the 5.56 tracer, which is really long...longer than any jacketed lead 77-80gr is going to be. Long bullets need a faster twist to stabilize. At some point, you can't stabilize and have to go the fin stabilized sabot/smoothbore route. Never heard of a civilian arm that needed to do that, though.
Military wanted 1:9 or 1:8 but needed 1:7. I have two 1:8 20" guns that shoot great, but I don't demand cloverleafs at 100 yards like some guys do.
_________________ "Wherever you go, there you are."
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Thu Apr 27, 2017 7:57 pm |
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Guns4Liberty
Site Supporter
Location: Lynnwood/Bothell Joined: Thu Jul 31, 2014 Posts: 8552
Real Name: Curtis
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1:7 is just fine. Shoot the lighter, cheaper bullets when pinpoint accuracy isn't required; when it is, just step up to heavier bullets.
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Thu Apr 27, 2017 8:42 pm |
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das_napeth
In Memoriam
Location: Snohomish Joined: Wed May 11, 2011 Posts: 1587
Real Name: Dan
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My FS2000, Tavor, Daniel Defense pencil, Spikes LE and 2 PSA barrels are 1:7. Have a few 1:8 and 1:9 as well. Honestly, i dont chase groups though so depending what you want. The way i shoot them with my purpose, havent been able to tell the difference.
_________________ Eff 594 and 1639
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Thu Apr 27, 2017 8:53 pm |
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beckdw
Site Supporter
Location: Tri -Cities Joined: Thu May 23, 2013 Posts: 2798
Real Name: David
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1:9 is the way to go for 55gr. My 1:8 18" shoots 2" groups at 100yds with 55gr. With 69gr match (Prvi mind you), I'm hitting 1" groups at 300yds. Hard to find good barrels in 1:9 longer than 16" though.
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Thu Apr 27, 2017 10:59 pm |
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