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Posted: 3/6/2010 4:12:33 PM EDT
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Im looking to replace the barrel that came with my Bushmaster XM15-E2S. Ive seen the videos and have the tools to do it, seems simple enough.,
but what has me stuck is the gas tube situation. Some barrels I see don't even mention the needed gas tube length.. others say NOTE: This barrel requires a full size, rifle length gas tube due to it's gas port location. So the question I have is: How do I know what barrel(s) is compatible with my rifle? |
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Gas tubes come in three lengths corresponding to the three different gas systems used on AR-15s; they are carbine, mid-length and rifle. When you buy a new barrel just go ahead and buy a new gas tube with it. You should be able to use any of the three gas system configurations with your present upper receiver.
Typically 20" barrels are referred to as rifle length and use a rifle (or full length) gas tube. 16" barrels may have their gas port located at the carbine or mid-length position and the vendor's listing should specify that. If in doubt contact the vendor. |
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FSB = Front Sight Base
Carbine length should be 7”, Mid-Length should be 9” and Rifle length should be 12”. You can reconfigure your rifle to any size that you want when you do a barrel swap… The only thing is… if you reconfigure it to have a longer or shorter gas system than it had originally you may need to buy the appropriate size gas tube and hand guard to match. What exactly are you trying to accomplish????? What is the reason for the barrel swap????? There are countless configurations that one can do with the AR15 platform… the more detailed the info… the better targeted our advice can be to your needs. |
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Quoted:
I was going to get a second barrel for distance shooting. along with a different stock, grip and scope.. have 1 gun that I can swap stuff around on and go from a fun plinker than i burn cheap bulk ammo through, to a precision rifle I shoot my hand loads through. Might I suggest building another upper instead of constantly reconfiguring 1 upper… Keep your carbine upper as it is and build a precision / long range upper for distance. Put a Magpul UBR stock on your lower, as that will work well for both applications. Then all you will have to do to switch is pop the pins and switch uppers to change from plinker to long range tack driver. |
| Im not going to swap between the 2 on an hourly basis or anything.. one weekend go can murdering with friends, the next shoot targets at the range.. so "ease" of doing it really doesent come into play. I actually LIKE taking the gun apart and putting it together.. hehe big boy legos. |
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Quoted:
Right well, considering getting a whole new upper is not what im doing. All i need i a gas tube and hand guard that is appropriate length (rifle or mid) for the barrel I buy. Cool. Pretty much… but I would strongly suggest having a complete barrel assembly (delta ring assembly w/ barrel nut… front sight base / gas block… gas tube... hand guards… flash hider / muzzle brake) You don’t need a complete separate upper, but you really don’t want to have to swap the parts that I listed above between barrels…. (Especially the front sight base / gas block…that goes double if its pinned!!) |
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You do NOT want to continually be swapping barrels on your upper. It was not designed for that and the potential for premature wear or incorrect assembly is too high.
Doing a barrel swap is a fairly involved job depending on your configuration, and it puts a lot of stresses on your upper forging and other parts. Also, have you considered that you would have to re-zero your rifle every time you swapped your barrels back and forth? Running 2 or more complete uppers is the correct answer... Even they can get sickening to always be swapping, so you will eventually end up buying another lower too... lol |
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