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Mid length had guard does not fit mid length gas system.


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13 hours ago, survivalshop said:

  AR 10 Barrel Nut has different thread pitch & the two are not inter changeable . Measuring or comparing a DPMS to an AR 10 will not help , AR 10 uses a different length in the gas systems , I believe .

OK, I found a post listing various barrel nut threads.

Barrel Nut Threads .png

Edited by archangel2003
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  I knew I had this somewhere & have posted it before . This may be incomplete & I don't see a Mid length for the AR 10 , but there may be one . If anyone see's any thing incorrect , please let me know . I remember researching for this a bit ago .

 

GAS TUBE LENGTH's 

 

Pistol---  4.5"

Carbine - 7.5"

Mid.----- 9.5"

Rifle ----- 13"

 

Armalite lengths,

Rifle ( 308 ) ----- 15.5 "

Carbine ( 308 )--12 1/16"

super SASS Carbine ( 308 )--11"

Super SASS< Rife (308 )   ?

Mid ,( 223 )------------------ 11 3/4"

Carbine ( 223) --------------- 9 3/4 "

Rifle ( 223 ) ------------------- 15 3/16"

 National Match---------------  ?

 

This is from the Armalite Tech. section, they are calling it a Mid length Carbine ? 

 

GAS TUBE LENGTH 

 

•M-15 rifle – 15-3/16” 

•M-15 mid length carbine – 11-3/4” 

•M-15 shorty carbine – 9-3/4” 

•AR-10 rifle – 15-1/2” 

•AR-10 mid length carbine – 12-1/16” 

 

All gas tubes: .180 OD and .117 ID

 

.

Edited by survivalshop
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1 hour ago, survivalshop said:

  I knew I had this somewhere & have posted it before . This may be incomplete & I don't see a Mid length for the AR 10 , but there may be one . If anyone see's any thing incorrect , please let me know . I remember researching for this a bit ago .

GAS TUBE LENGTH

•M-15 rifle – 15-3/16” 

•M-15 mid length carbine – 11-3/4” 

•M-15 shorty carbine – 9-3/4” 

•AR-10 rifle – 15-1/2” 

•AR-10 mid length carbine – 12-1/16” 

All gas tubes: .180 OD and .117 ID

Every source I found says that the gas tubes for the AR-15 and the AR-10 are the same length no matter the gun length/size.

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 We've troubleshot quite a few builds here that were short stroking because the The barrels gas port was built to AR10 spec, and the standard gas tube wasn't quite long enough. Swapping to the AR10 specific rifle length gas tube fixed the issue. It can even happen with DPMS based builds if the barrel manufacturer happened to have use Armalite gas port location. 

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If I were to mark the gas tube as it's mounted, then take the gas block off and push the tube in further, how much free play/clearance should it take up before touching the bolt gas tube receiver?

Also, to measure the gas port location on the barrel, what is the reference point we measure from?

In my case, the gas port would need be to be further away from the chamber making the gas tube possibly hit if it were too close.

Edited by archangel2003
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   According to your photo of where the Gas tube protrudes into the Upper receiver , you have the correct orientation .

   I will say this again , if you plan is to use those hand guards , you will need to fit them to your rifle. If you are reluctant to do so , get a proper Free Float Hand Guard .

  I posted those Gas Tube lengths to show the difference between AR 10 & DPMS/AR 15 , your Gas tube or the Gas blocks relationship or distance between the Barrel Nut is correct for that Barrel /Nut/Upper Receiver . You can not adj. the Gas Block to suit your Hand Guard configuration , you will just cut off or restrict your gas signal to the BCG ..

  Most Barrels Made today the Barrel's Gas Block stop flange is cut to use a Gas Block for a FF Hand Guard & not for A2 Types . If you get a Barrel with an A2 Sight pinned on it , it may have the correct orientation for the use of the A2 type Hand Guards . That's not written in stone because of no Common spec's for the 308 AR & manufacturers do what ever suits their needs , even if its proprietary . Good luck on your endeavor .

Edited by survivalshop
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OK, I took the advise and pulled out the razor knife, files and used the belt grinder.

First 2 pictures.

I took the all the internal parts off the back end where the hand guards locate under the Delta Ring.

Next 2 pictures.

I then ground the front inner tabs level with the outer tabs, then took down the triangle end cap to match and the second is it installed.

Next Picture.

All that was not enough so the part that the delta ring grabs that were too long were shortened.

Next 2 Pictures.

The retaining tabs for the delta ring were still in the way so off they came.

Yeah, with the hand guards off the delta ring and spring will be loose but not something I'm worried about.

After all that, they now fit, just don't look too close when they are apart.

The last picture is it installed at the Delta Ring.

 

 

1A Before.jpg

1B After.jpg

2A Before.jpg

2B After.jpg

2C After Front.jpg

1C After Rear.jpg.jpg

20160425_130640.jpg

20160425_134147.jpg

20160425_144543.jpg

Edited by archangel2003
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