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Posted: 10/19/2010 10:16:52 PM EDT
| Very new to AR-15 world. Looking to build my first ar-15. For my upper, which is better 1X9 or 1X7? |
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It depends on what weight bullets you want to shoot, nothing to do with pressure at all.
If you want to shoot heavier (in the 69-77gr range) you would be better served with the 1 in 7" twist. Though it is perfectly capable of handling 55gr cheapo ammo, it just doesn't shoot them as well as the 1 in 9". If you want to shoot lighter (lighter than 69gr) you should stick with 1 in 9" twist. Though it is perfectly capable of shooting the 70gr+ stuff, they just don't stabilize as well for longer ranges. What you should look at as well is the chamber, is it 5.56NATO, .223REM, or .223Wilde. The 5.56NATO will shoot anything, as will the Wilde I'm told, but the .223REM should only be used to fire .223REM ammunition because the military (NATO) rounds have a bit different dimensions and will cause an increase in pressure if fired in a .223REM chamber. ETA: Buy this and call it a day. |
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Quoted:
Welcome, i just finished building my first AR15. Do you mean 1 and 7 twist or 1 and 9 twist? If so you should go with a 1 and 7 twist, it handles the pressure of the 556 round better. Not sure if thats the info you needed Wrong. Quoted:
It depends on what weight bullets you want to shoot, nothing to do with pressure at all. If you want to shoot heavier (in the 69-77gr range) you would be better served with the 1 in 7" twist. Though it is perfectly capable of handling 55gr cheapo ammo, it just doesn't shoot them as well as the 1 in 9". If you want to shoot lighter (lighter than 69gr) you should stick with 1 in 9" twist. Though it is perfectly capable of shooting the 70gr+ stuff, they just don't stabilize as well for longer ranges. What you should look at as well is the chamber, is it 5.56NATO, .223REM, or .223Wilde. The 5.56NATO will shoot anything, as will the Wilde I'm told, but the .223REM should only be used to fire .223REM ammunition because the military (NATO) rounds have a bit different dimensions and will cause an increase in pressure if fired in a .223REM chamber. ETA: Buy this and call it a day. Mostly right. |
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Quoted:
Quoted:
Welcome, i just finished building my first AR15. Do you mean 1 and 7 twist or 1 and 9 twist? If so you should go with a 1 and 7 twist, it handles the pressure of the 556 round better. Not sure if thats the info you needed Wrong. Quoted:
It depends on what weight bullets you want to shoot, nothing to do with pressure at all. If you want to shoot heavier (in the 69-77gr range) you would be better served with the 1 in 7" twist. Though it is perfectly capable of handling 55gr cheapo ammo, it just doesn't shoot them as well as the 1 in 9". If you want to shoot lighter (lighter than 69gr) you should stick with 1 in 9" twist. Though it is perfectly capable of shooting the 70gr+ stuff, they just don't stabilize as well for longer ranges. What you should look at as well is the chamber, is it 5.56NATO, .223REM, or .223Wilde. The 5.56NATO will shoot anything, as will the Wilde I'm told, but the .223REM should only be used to fire .223REM ammunition because the military (NATO) rounds have a bit different dimensions and will cause an increase in pressure if fired in a .223REM chamber. ETA: Buy this and call it a day. Mostly right. This is it. |
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Buy the 1:7. A 1:9 will not stabilize lighter weight bullets better, despite what some people claim. Molon has made some posts about this previously.
ETA: Here is one link from Molon about the 1:9 vs. 1:7. Bottom of the first post. You can see that the 1:7 actually performed better with XM193 clone 55 gr. cartridges. |
| If you have any interest in heavier bullets, go 1/7. 1/9 twist is limited because it doesn't stabilize the heavier bullets and the 1/7 will shoot all ammo well instead of limiting yourself to 55 gr. If you ever get interested in shooting longer distances you'll be wishing for heavier bullets. Most people underestimate the capabilities of a quality 16" upper as far as max distance while using good ammo, although you do run out of energy before accuracy, it depends on what the gun is being used for. Crows or p dogs at 400-600 yards with a 16" 5.56 is my idea of fun. |
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A light barrel will vibrate. A heavy barrel will still vibrate but not as much. The heavy barrel is more stable giving better groups.
A light barrel has dips between the receiver and sight post. The heavy barrel is a solid width out to the sight post where is steps down to the muzzle. Holds groups better. The bull barrel would be good on a bolt action rifle with a 1 in 8 twist at 26" or better shooting 65 to 80 HP. Better p dog gun out to 600 yards. Some will shoot out to 1000 depending on the builder. If you are going to shoot Wal Mart 55 grain, stay with the 1 in 9 twist. You could stay with the 16 to 20 inch length. |
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Quoted: Welcome, i just finished building my first AR15. Do you mean 1 and 7 twist or 1 and 9 twist? If so you should go with a 1 and 7 twist, it handles the pressure of the 556 round better. Not sure if thats the info you needed I am getting a lot of complaints about people posting false information in here, please think twice about what you post.  |
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I've shot plenty of 55grain out of a 1/7. Personally I would get 1/7 if you have the option, although I suspect that 99% of people get by just fine with 1/9. As far as the style of barrel, it depends what you want it for. I have an m4 profile barrel simply because that's what most good barrels for carbines are. Personally for my uses I would not bother with an hbar; but I'm not coyote hunting with my carbine.
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Quoted:
Quoted:
Welcome, i just finished building my first AR15. Do you mean 1 and 7 twist or 1 and 9 twist? If so you should go with a 1 and 7 twist, it handles the pressure of the 556 round better. Not sure if thats the info you needed I am getting a lot of complaints about people posting false information in here, please think twice about what you post. Hey, I wrote earlier that i was sorry for the wrong info, i used the wrong word in my reply. Was not intentional. It had been a long day working on the ambulance. |
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