308 gas tube question

[JerryPbury]

Just finished my first .308 AR assembly. 20" barrel, midlength gas block. I purchased a DPMS 308 "compatible" gas tube. It just doesn't look long enough. It just clears the notch in the upper. It's installed right now but I'm not too sure about shooting it tomorrow. How far should it protrude into the Notched area (next to the charging handle slot)? I'm used to the tube extending half way into the notched area on an AR15. The 308 notch is at least twice the size of the AR15.

Any recommendations for the "correct tube"?

Thanks for any suggestions.

Jerry

Edited August 22, 2016 by JerryPbury
Repeated question

[beantown]

On my box stock DPMS LR-308 mine is that not far into where the notch is. Let me snap a pic of it for you.

[shepp]

1 hour ago, JerryPbury said:

Just finished my first .308 AR assembly. 20" barrel, midlength gas block. I purchased a DPMS 308 "compatible" gas tube. It just doesn't look long enough. It just clears the notch in the upper. It's installed right now but I'm not too sure about shooting it tomorrow. How far should it protrude into the Notched area (next to the charging handle slot)? I'm used to the tube extending half way into the notched area on an AR15. The 308 notch is at least twice the size of the AR15.

Any recommendations for the "correct tube"?

Thanks for any suggestions.

Jerry

Welcome to the forum, feel free to post in the intro section from what you say it sounds short.

 

Its gotta be long enough to go into the gas key on your bcg

Edited August 23, 2016 by shepp

[survivalshop]

  There were a couple of Carbine gas system Tubes that did't go to far in & they said they work . I think some gas Blocks are not set up correctly or the Barrels are not , hard to say.

[beantown]

Here is my box stock LR-308.

[JerryPbury]

Mines like this^^^^^^

[JerryPbury]

14 minutes ago, shepp said:

Welcome to the forum, feel free to post in the intro section from what you say it sounds short.

 

Its gotta be long enough to go into the gas key on your bcg

This is what I was thinking it should look like.

[beantown]

Like I said Jerry mines a factory DPMS built rifle. I have had no issues at all with it.

[JerryPbury]

19 minutes ago, shepp said:

Double post

Edited August 23, 2016 by JerryPbury

[JerryPbury]

I'll try it at the range tomorrow and post results.

 

Thank you all!

[shepp]

1 minute ago, beantown said:

Like I said Jerry mines a factory DPMS built rifle. I have had no issues at all with it.

Like wise

[survivalshop]

  I still wouldn't like it , because we have had some here that wouldn't work when they were like that . I still say there is something to it by DPMS & I say this because there are only a few that are like this shorter version . 99% of what I have seen are in the middle or very close to it . Tolerance spec's by DPMS , maybe they changed something or something got past QC . JMHO.

[JerryPbury]

Went to the range this morning. Put 40 rounds through it without a problem. Ejected @3 o'clock into a nice group 8 feet away. Locked back on the empty mag. Need to go back and dial in my scope. I am very happy!

i did go ahead and order the longer Armalite gas tube.

[mrmackc]

Just remember that the gas tube has to enter the gas key far enough too give the pressured gas volume enough energy to push against the bolt gas rings,to keep the bolt from unlocking prematurely and then cycle the BCG fully open and compress the buffer spring

[survivalshop]

4 hours ago, JerryPbury said:

Went to the range this morning. Put 40 rounds through it without a problem. Ejected @3 o'clock into a nice group 8 feet away. Locked back on the empty mag. Need to go back and dial in my scope. I am very happy!

i did go ahead and order the longer Armalite gas tube.

  Which one or size ?

 

DPMS Gas Tube/AR 15/16

 

  Pistol             6-5/8

  Carbine          9-3/4

  Mid-Length  11-3/4

  Rifle             15-1/4

 

 

 

 

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---------------  ?

 

[JerryPbury]

The Armalite Carbine. It gives me 5/16" more which should put me where I want to be.

[survivalshop]

   

On August 23, 2016 at 7:16 PM, JerryPbury said:

The Armalite Carbine. It gives me 5/16" more which should put me where I want to be.

   You say you have a Mid Length gas system on that 20" barrel ? I'm confused on how the Armalite Carbine Gas Tube is going to be longer .

[DNP]

Per your chart. 308 carbine 12 1/16 minus DPMS mid 11 3/4 = 5/16. 

[JerryPbury]

What he said^^^^^^?

[survivalshop]

On August 25, 2016 at 6:55 AM, DNP said:

Per your chart. 308 carbine 12 1/16 minus DPMS mid 11 3/4 = 5/16. 

Oh , dooooo!

[mrmackc]

On 8/23/2016 at 1:31 PM, JerryPbury said:

Went to the range this morning. Put 40 rounds through it without a problem. Ejected @3 o'clock into a nice group 8 feet away. Locked back on the empty mag. Need to go back and dial in my scope. I am very happy!

i did go ahead and order the longer Armalite gas tube.

So you only needed a good magazine to shoot a perfect course of 40 rounds? with the new DPMS rifle ......So you went ahead and ordered a gas tube that is for a Armalite carbine, and you have a rifle length DPMS rifle.   Now why in the hell would you do that?

[COBrien]

Looks to me like it's a DIY mid-length setup (not factory built), and the DPMS mid-length tube (11-3/4") appeared to be too short. The ArmaLite .308 carbine tube (12-1/16") was "just right," being 5/16" longer.

Turns out the rifle runs just fine with the DPMS Mid, but he ordered the ArmaLite Carbine tube for peace of mind.

Not sure where the confusion lies...

[JerryPbury]

Yup^^^^^?

[mrmackc]

OOPS! Sorry I got the wrong Dude, on the wrong thread. My first mistake today.

[survivalshop]

2 hours ago, mrmackc said:

OOPS! Sorry I got the wrong Dude, on the wrong thread. My first mistake today.

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