Having trouble with a build

[Thumper]

New to this (or any other) Forum. I'm looking for some advice on what to do about the function of my rifle. 

Here is what I put together:

1. Aero Precision lower
2. Gibbz Arms G10 Upper
3. FailZero BCG
4. Ballistic Advantage Heavy 1:10 20" Barrel
5. GunTec MilSpec Buffer Tube Kit
6. Rise Armement 3.5# Trigger
7. Adjustable Gas Block
8. Etc...

The rest of the parts are Daniel Defense, Magpul, Nikon, and so on.

It shoots wonderful, sub MOA gun. However it will not lock the bolt back on a empty magazine or pick up the next round on a full mag. I have tried adjusting the gas block from not ejecting to just shy of all the way out. I have tried 5 different brands of ammo plus some loads I made up for this gun to start developing, and 3 different magazines. 

Any advice or other suggestions would be greatly appreciated.

 

[washguy]

Hey Thumper                    Welcome to the forum     How many rounds down the tube? new rifle? you got her lubed up real good?

so the first function check is always will she lock back on last round? I guess you know that.... so lets concentrate on one round and getting her to lock back..these ar308s can drive you nutz when they are new with a low round count . Sounds like you are pretty damn close ...heres what I would look at is the buffer the spring and tube...sounds like shes got enough gass....and it could also be the bcg dragging just a bit....lemme go look at this guntec kit...you gotta make sure you are using the ar308 spring and buffer  ill be back      Wash

http://www.guntecusa.com/index.php?route=product/product&product_id=530&search=308+buffer

is this the one you have? and the bolt catch ..some are better than others...you are close also shot gun the ar.. muzzle down.. drop  in the bcg...should almost go into battery....making sure the bcg isnt hitting anything and the gas tube is letting the bcg go  into battery

 

Edited September 12, 2016 by washguy

[98Z5V]

11 minutes ago, Thumper said:

New to this (or any other) Forum. I'm looking for some advice on what to do about the function of my rifle. 

Here is what I put together:

1. Aero Precision lower

 

What lower parts kit did you use - specifically, what bolt catch?

Also, combining different manufacturers' uppers and lowers leads to the most problems we see.  No kidding.  It might not come to that, in this case, but it happens frequently.

[Thumper2]

1 hour ago, washguy said:

Hey Thumper                    Welcome to the forum     How many rounds down the tube? new rifle? you got her lubed up real good?

so the first function check is always will she lock back on last round? I guess you know that.... so lets concentrate on one round and getting her to lock back..these ar308s can drive you nutz when they are new with a low round count . Sounds like you are pretty damn close ...heres what I would look at is the buffer the spring and tube...sounds like shes got enough gass....and it could also be the bcg dragging just a bit....lemme go look at this guntec kit...you gotta make sure you are using the ar308 spring and buffer  ill be back      Wash

http://www.guntecusa.com/index.php?route=product/product&product_id=530&search=308+buffer

is this the one you have? and the bolt catch ..some are better than others...you are close also shot gun the ar.. muzzle down.. drop  in the bcg...should almost go into battery....making sure the bcg isnt hitting anything and the gas tube is letting the bcg go  into battery

 

Couldn't get in the forum by my original login password. So here I am as 2. I've got about 50 rounds shot so far, with the malfunction I haven't spent much time at the range with it. Let me clarify something. It has never locked the bolt back after the last round, however, it has picked up the next round about 5-6 times, but never more that twice in a row. I can pull the BCG out from battery about an inch and drop it and it goes into battery no issues. It's lubed well, no issues there. Bolt catch image below. 

[Thumper2]

2 hours ago, 98Z5V said:

What lower parts kit did you use - specifically, what bolt catch?

Also, combining different manufacturers' uppers and lowers leads to the most problems we see.  No kidding.  It might not come to that, in this case, but it happens frequently.

I'm not sure what brand lower parts kit it was. We put everything together at the shop where I bought all the parts.

[Thumper2]

2 hours ago, washguy said:

Hey Thumper                    Welcome to the forum     How many rounds down the tube? new rifle? you got her lubed up real good?

so the first function check is always will she lock back on last round? I guess you know that.... so lets concentrate on one round and getting her to lock back..these ar308s can drive you nutz when they are new with a low round count . Sounds like you are pretty damn close ...heres what I would look at is the buffer the spring and tube...sounds like shes got enough gass....and it could also be the bcg dragging just a bit....lemme go look at this guntec kit...you gotta make sure you are using the ar308 spring and buffer  ill be back      Wash

http://www.guntecusa.com/index.php?route=product/product&product_id=530&search=308+buffer

is this the one you have? and the bolt catch ..some are better than others...you are close also shot gun the ar.. muzzle down.. drop  in the bcg...should almost go into battery....making sure the bcg isnt hitting anything and the gas tube is letting the bcg go  into battery

 

Looks like the exact buffer tube and spring that's in it.

[survivalshop]

interesting Bolt Catch you have there , Looks like a real rough cast or made from that powdered Metal forming . If the rifle is stripping fresh rounds some of the time , but not locking back on last round fired , it may need more or different lubricant & higher break round count , as has been said . 98 is correct , we seem to see a lot of issues with non compatible Receivers , but there is always a way around it . 

     -Can you lick back the BCG manually & will it lock back with a empty Mag inserted when charged to the rear fully ?

     - Measure & count the coils on the Buffer Spring 

       -Measure the length of the Buffer & weigh it , if you can.

       - Could also be an issue with gas system , could be an adj. issue , some have a locking set screw before the adjuster that has to be removed before adjusting .ya never know , just putting it out there .

   

Edited September 13, 2016 by survivalshop

[Thumper2]

11 minutes ago, survivalshop said:

interesting Bolt Catch you have there , Looks like a real rough cast or made from that powdered Metal forming . If the rifle is stripping fresh rounds some of the time , but not locking back on last round fired , it may need more or different lubricant & higher break round count , as has been said . 98 is correct , we seem to see a lot of issues with non comparable Receivers , but there is always a way around it . 

     -Can you lick back the BCG manually & will it lock back with a empty Mag inserted when charged to the rear fully ?

     - Measure & count the coils on the Buffer Spring 

       -Measure the length of the Buffer & weigh it , if you can.

       - Could also be an issue with gas system , could be an adj. issue , some have a locking set screw before the adjuster that has to be removed before adjusting .ya never know , just putting it out there .

   

Spring is 27 coils from end to end, buffer is 2 1/2 inches long. I don't have a scale that will weigh it though. It will lock back manually with an empty magazine in it. It has only loaded the next round a half a dozen times at most but never more than twice in a row. As far as the bolt catch goes, it's pretty smooth. That's a really close up pic with a lot of light. 

[survivalshop]

  How long is the Buffer Spring , end to end ?

 Was the G10 Upper a complete unit assembled ?

[Thumper2]

8 minutes ago, survivalshop said:

  How long is the Buffer Spring , end to end ?

 Was the G10 Upper a complete unit assembled ?

The spring is 11" long. I bought the upper receiver, BCG, and barrel as separate pcs. 

[washguy]

Thumper      okay looks like you have the proper 308 buffer spring and buffer.....and since its a complete kit the buffer tube should be right also.

when pulling the charge handle back without mag how much further does it go back past the bolt catch?...or to put it another way let the bcg be locked back on the bolt catch...then pull back the handle to see how much further back it will go.Bcg has to go back a tad farther than the catch, The bcg has to lockback...so its one bullet in mag till it does....if you have the proper buffer , buffers spring and tube in there..then its a gas problem prolly....you might also check the chamber making sure its smooth in there......you are close....what ammo exactly are you using for break in?         Wash

[RRS]

5 hours ago, 98Z5V said:

What lower parts kit did you use - specifically, what bolt catch?

Is the Aero Precision LPK paired with the AP M5 receiver set the right way to go, or is there another LPK we should be using?

[survivalshop]

  If you assembled the Barrel assembly , you might want to check to make sure the Gas Block it orientated correctly with the Gas Port in the Barrel . 

[Thumper]

3 hours ago, survivalshop said:

  If you assembled the Barrel assembly , you might want to check to make sure the Gas Block it orientated correctly with the Gas Port in the Barrel . 

I had a non-adjustable on it at first, changed it last week to an adjustable. That's been checked by eye and air.

[Thumper]

9 hours ago, washguy said:

Thumper      okay looks like you have the proper 308 buffer spring and buffer.....and since its a complete kit the buffer tube should be right also.

when pulling the charge handle back without mag how much further does it go back past the bolt catch?...or to put it another way let the bcg be locked back on the bolt catch...then pull back the handle to see how much further back it will go.Bcg has to go back a tad farther than the catch, The bcg has to lockback...so its one bullet in mag till it does....if you have the proper buffer , buffers spring and tube in there..then its a gas problem prolly....you might also check the chamber making sure its smooth in there......you are close....what ammo exactly are you using for break in?         Wash

I started out with Hornady 155gr Amax, then I found this problem I'm having. I've shot Remington, Winchester 7.62X51, Federal, American Eagle (Federal), and hand loads. Hand loads are Hornady match cases, WLR Primers, 39.9g Varget, 168gr SMK's. All .308 rounds except the Winchesters. I wouldn't have switched up ammo if I wasn't looking for the resolution to this problem. Everyone I talked to said to change up the ammo and magazines, so I did. 

[survivalshop]

  Can you supply a photo of the Gas tube as it sits inside the Upper Receiver , it should look like this ,in relation to the Cam Pin recess in the Upper Receiver. It should be somewhere in the center of it .

Just blowing air down the Gas Tube is not proof it it will allow the proper Gas signature to the BCG . A lot of these Gas Blocks Now a days , both Clamp on & Set Screw types ,have the Screw hole nearest the Barrel Stop flange for the Gas Block on the Barrel , that is used to drill the Port hole in the Gas Block , You can , with the Gas tube removed , flip the gas Block 180deg. so its on top of the Barrel , so as to see its orientation with the Barrels Gas Port & use a Feeler gage or other measuring device , so when the Gas Block is orientated in its proper position , it can be spaced or set accordingly .

 Also when Gas Block is off or out of position , you can measure the Gas port hole size in the Barrel , Drill Bits work good enough to get close to the size measurement . I'm assuming the Gas system is a Rifle Gas system . 

Edited September 13, 2016 by survivalshop

[washguy]

Thumper   " I started out with Hornady 155gr Amax, then I found this problem I'm having. I've shot Remington, Winchester 7.62X51, Federal, American Eagle (Federal), and hand loads. "      so did the rifle cycle with Hornady 155Amex ? Those other loads are kinda weak. How much past the bolt catch can you pull the charge handle...you get a chance to do this?  Comes across as being under gassed or bcg dragging you drop the bcg down the barrel while pointed down?...new gun blues....does it eject with authority?

Wash

[Thumper2]

1 hour ago, washguy said:

Thumper   " I started out with Hornady 155gr Amax, then I found this problem I'm having. I've shot Remington, Winchester 7.62X51, Federal, American Eagle (Federal), and hand loads. "      so did the rifle cycle with Hornady 155Amex ? Those other loads are kinda weak. How much past the bolt catch can you pull the charge handle...you get a chance to do this?  Comes across as being under gassed or bcg dragging you drop the bcg down the barrel while pointed down?...new gun blues....does it eject with authority?

Wash

I can pull the BCG out of battery about an inch and with the muzzle pointed down it goes all the way into battery when dropped. That's not an issue. It ejects, from what I can tell, at about a 4 oclock angle. Believe it or not it only picked up the next round with the Winchester 7.62X51 ammo, but only a few times. I tried adjusting the gas block with that ammo and never it cycled right, and never on the 155 AMAX, not even once. The charge handle comes past the bolt catch right at 3/16ths. Manually, I can strip 25 rounds out of a magazine, no issues, so I don't think travel length is the issue. Everything lines up, the gas tube is the correct length, gas block is orientated correctly. Do you happen to know what size hole the gas port in the barrel is supposed to be? Can you drill the hole bigger if it's under gassed? or what is the solution for an under gassed gun? A softer spring on the buffer? 

[98Z5V]

In the scenario of a non-adjustable gas block, the only issue for an undergassed gun is to drill up the gas port.

 

As long as you're sure the adjustable gas block isn't the issue, might as well yank it off and measure the gas port diameter in the barrel.  Even a wide-open adjustable gas block isn't gonna deliver enough gas pressure, if that gas port is undersized.

Report the result of the gas port size in this thread - we have a pretty good idea is what you'll need, diameter-wise, and we'll certainly recognize a too-small port diameter.

[Thumper]

The diameter of the hole is a tight .086 measured with the shank end of a  # 44 drill bit.

[Thumper]

If anyone is wondering why I keep going back and forth between 2 names, I am having a heck of a time logging in. It keeps locking me out and I have to reset my password every time. I've contacted the admin about it but haven't heard back. pretty frustrating.

[Thumper]

7 hours ago, survivalshop said:

  Can you supply a photo of the Gas tube as it sits inside the Upper Receiver , it should look like this ,in relation to the Cam Pin recess in the Upper Receiver. It should be somewhere in the center of it .

Just blowing air down the Gas Tube is not proof it it will allow the proper Gas signature to the BCG . A lot of these Gas Blocks Now a days , both Clamp on & Set Screw types ,have the Screw hole nearest the Barrel Stop flange for the Gas Block on the Barrel , that is used to drill the Port hole in the Gas Block , You can , with the Gas tube removed , flip the gas Block 180deg. so its on top of the Barrel , so as to see its orientation with the Barrels Gas Port & use a Feeler gage or other measuring device , so when the Gas Block is orientated in its proper position , it can be spaced or set accordingly .

 Also when Gas Block is off or out of position , you can measure the Gas port hole size in the Barrel , Drill Bits work good enough to get close to the size measurement . I'm assuming the Gas system is a Rifle Gas system . 

 

7 hours ago, survivalshop said:

  Can you supply a photo of the Gas tube as it sits inside the Upper Receiver , it should look like this ,in relation to the Cam Pin recess in the Upper Receiver. It should be somewhere in the center of it .

Just blowing air down the Gas Tube is not proof it it will allow the proper Gas signature to the BCG . A lot of these Gas Blocks Now a days , both Clamp on & Set Screw types ,have the Screw hole nearest the Barrel Stop flange for the Gas Block on the Barrel , that is used to drill the Port hole in the Gas Block , You can , with the Gas tube removed , flip the gas Block 180deg. so its on top of the Barrel , so as to see its orientation with the Barrels Gas Port & use a Feeler gage or other measuring device , so when the Gas Block is orientated in its proper position , it can be spaced or set accordingly .

 Also when Gas Block is off or out of position , you can measure the Gas port hole size in the Barrel , Drill Bits work good enough to get close to the size measurement . I'm assuming the Gas system is a Rifle Gas system . 

 

[98Z5V]

1 hour ago, Thumper said:

The diameter of the hole is a tight .086 measured with the shank end of a  # 44 drill bit.

That's a touch on the small size.  What gas system is this - carbine, midlength, or rifle?  What's the approximate length of the gas tube, if you're not sure of the gas system?

[washguy]

2 hours ago, Thumper said:

The diameter of the hole is a tight .086 measured with the shank end of a  # 44 drill bit.

Yep. If it rifle length it needs to be opened a touch.....44 is the size .086 I use in most all of my rifles. 44/45 but they are all mid length.     you are just a tad undergassed  ...and your bcg is going into battery... drill that sucka out..but you could do one last thing...get a 12 gauge bore mop put some flitz on the mop and polish the chamber with the mop in a  drill....that might be all it needs you would be surprised how that has helped folks.    Wash

Go look up the excaliber thread and its gasport and not cycling

Edited September 14, 2016 by washguy

[survivalshop]

  Check this Faxon firearms , just for comparison their 20" rifle length gas , Port size is .093 " 

http://faxonfirearms.com/20-heavy-fluted-308-win-rifle-length-416-r-stainless-steel-qpq/