Is my gas tube to short?

[Bozzman3]

It looks a bit short to me.

 

[mrmackc]

Question, is the rifle performing properly? Have you broken it in as per the Manufacturer's recommendation, and did you really lube up the BCG before firing it.  Maybe it is a silly millimeter or 3 too short.  Is it a factory built or home grown, or previously used and abused ? Don't look to be new out of the box.

And what is it's name? DPMS, Winchester, High Point, S&W? Armalite?

[Bozzman3]

It’s a cobbled together rifle from a local gunsmith using a PSA gen 3 lower.It has 20 inch barrel with a 7 buffer tube.The buffer is a kaw valley 5.6oz 2.5 inch with a JP extra power .308 carbine Spring.The gun will chamber a round  from a bolt drop  and fire and extract the empty fine.It rarely self loads another round.The bolt seems to just ride over the next round and closes on a empty chamber.If I pull the charging handle I can repeat the process.On the last round the bolt doesn’t stay open unless I pull the charging handle on a empty mag.I know it’s not the mag because I have 3 different brands.Any and all advice is appreciated.

[98Z5V]

24 minutes ago, Bozzman3 said:

It’s a cobbled together rifle from a local gunsmith using a PSA gen 3 lower.It has 20 inch barrel with a 7 buffer tube.The buffer is a kaw valley 5.6oz 2.5 inch with a JP extra power .308 carbine Spring.The gun will chamber a round  from a bolt drop  and fire and extract the empty fine.It rarely self loads another round.The bolt seems to just ride over the next round and closes on a empty chamber.If I pull the charging handle I can repeat the process.On the last round the bolt doesn’t stay open unless I pull the charging handle on a empty mag.I know it’s not the mag because I have 3 different brands.Any and all advice is appreciated.

Based on that description, your gas system isn't cycling the BCG fully/properly.  Yes, that gas tube is too short, and I'll bet that your gas port diameter is too small.  That combination is preventing the gun from functioning like it should.

What's the brand of the barrel, what's the gas system, what's the gasport diameter...  All we know right now is that it's a 20" barrel.  Probably Rifle Gas, doubt it's Midlength.

Edited April 12, 2020 by 98Z5V

[Bozzman3]

I believe it’s rifle gas see picture below.I unscrewed the gas block and the gas port on the barrel is between .062-.078.The gas block is 1 piece and I am not sure how it comes off due to a ring at the end of the barrel.There are no markings on the barrel besides .308 win 1/10

,

[98Z5V]

10 minutes ago, Bozzman3 said:

I believe it’s rifle gas see picture below.I unscrewed the gas block and the gas port on the barrel is between .062-.078.The gas block is 1 piece and I am not sure how it comes off due to a ring at the end of the barrel.There are no markings on the barrel besides .308 win 1/10

,

That's a huge difference in what it could be.  Doesn't matter, though, because you'll need a gasport diameter between 0.093"~0.096" to make that run gun.  That gas port diameter has to go up, or this thing is never gonna run right.  Might as well put a (real, genuine) Armalite AR-10 Rifle Gas Tube in there while you're at it.  Doing those two things will complete fix that gas system.  The Armalite Part # that you need for the gas tube is 10007010.

 

[Bozzman3]

So  I need to drill the barrel?What about the gas block does the orifice in the gas block need to be resized as well?How hard is it to drill a barrel?

[sketch]

use a titanium bit if possible and go slow and lube. not that hard. 

ps. dont take it all at once, start with smaller bits and work up to desired diameter. 

Edited April 12, 2020 by sketch

[98Z5V]

5 hours ago, Bozzman3 said:

So  I need to drill the barrel?What about the gas block does the orifice in the gas block need to be resized as well?How hard is it to drill a barrel?

The gas block will be fine.  It's already maxed out at 0.125". Stick a 1/4" wooden dowel down the barrel, so if you punch through too hard, you won't hit the rifling on the other side of the barrel.  Slow drill speed, and light pressure.Let the bit eat,and do the work. You push too hard (apply too much pressure) or go too fast, you'll break the drill bit off in the barrel. 

[Bozzman3]

Thanks Guys, I assume this is a rifle gas system?

[mrmackc]

7 hours ago, sketch said:

use a titanium bit if possible and go slow and lube. not that hard. 

ps. dont take it all at once, start with smaller bits and work up to desired diameter. 

Do as Sketch said,  also put a wood dowel in the barrel under the gas port to keep from running the drill bit into the bottom of the barrel, I didn't have a dowel so I used a round wood pencil, If you use a drill press use a bit just large enough to fit in the barrel to align   the barrel under the drill press chuck before you clamp it down with a drill press vice then raise the chuck take out the small bit and you are all set to chuck up a correct size bit and drill out the port.

[98Z5V]

6 hours ago, Bozzman3 said:

Thanks Guys, I assume this is a rifle gas system?

Measure the length of your gas tube.  That will tell you. If it's a tick over 15", then it's an AR15-based rifle gas tube.

Check this section out, too - TONS of info in here:

https://forum.308ar.com/forum/65-308-ar-what-you-need-to-know/

Edited April 12, 2020 by 98Z5V

[Bozzman3]

You guys really know the AR .308 platform.If it wasn’t for you guys my rifle would have never worked.The back story is this,I had a local gunsmith sell and build me .308 AR.(I supplied the lower)When I got the rifle home the bolt would not lock back and I couldn’t hand cycle rounds.Did research here and found out the wrong buffer and sprng were installed.Purchased the right combo of buffer and spring and installed them.Brought the rifle  to the range and the rifle now would short cycle and and not stay open on the last round.It never self loaded.I started asking questions about my gas tube and then was advised my gas port was to small.Brought the rifle back to the smith and had him drill out the port to.094.Took it to the range today and she functions perfectly! Thanks guys you are great!

[Armed Eye Doc]

Awesome 👍

Did you make the gunsmith pay for the parts you had to replace?  They should not have given you a rifle that didn't work, especially when it would not manually cycle and lock open.

[Bozzman3]

Yes he paid for the buffer and spring.But he did charge me for drilling the gas port.I purchased and had the gunsmith do it all so I wouldn’t have troubles.I should have just built and bought it myself.Lesson learned.I am glad I didn’t try and drill it he broke a bit in the firs5 barrel he tried to drill.

Edited April 23, 2020 by Bozzman3

[Matt.Cross]

3 minutes ago, Bozzman3 said:

Yes he paid for the buffer and spring.But he did charge me for drilling the gas port.

That's fair enough IMHO.

[Armed Eye Doc]

5 minutes ago, Matt.Cross said:

That's fair enough IMHO.

I would agree.

9 minutes ago, Bozzman3 said:

I purchased and had the gunsmith do it all

Unless you provided the parts, that might make me rethink it.  The gunsmith should have caught it before it left his shop.

It is all good now though.  Shoot her and enjoy her.

Edited April 24, 2020 by Armed Eye Doc

[mrmackc]

4 hours ago, Bozzman3 said:

Yes he paid for the buffer and spring.But he did charge me for drilling the gas port.I purchased and had the gunsmith do it all so I wouldn’t have troubles.I should have just built and bought it myself.Lesson learned.I am glad I didn’t try and drill it he broke a bit in the firs5 barrel he tried to drill.

There are skilled gunsmiths around and there are a lotta unskilled "gunsmiths"  around.   I  have learned along the way from being a young wanna be to where I am now, If you want something done right, first find out what is needed and then pace your self and do it, If you want something done right, do it yourself, and when it is doing okay, keep it to yourself, until that young wanna be kid needs your help, and help him know what is needed. Drilling a hole in a barrel is not like drilling a hole in a baseball bat, but with the right tools it can be done without a problem