Need help/advice!

[Epicersatz]

HI all,

I completed my first AR10 build some months ago and have been trying to troubleshoot an issue I am having.  I will list my specs then the issue.

It is a DPMS Pattern chambered in .308.

Aero m5 upper and lower

Aero Rifle buffer system (Buffer is 5.6oz and spring is 11.75 inches long uncompressed)

X-Caliber 18 inch barrel with rifle length gas system

Forward Control Design gas block (low profile, non adjustable)

Seekins BCG with double extractor

Radian Charging Handle

THe issue I am having some day one is it won't cycle properly.  It will eject at 3 oclock just fine, I have never had a failure to eject.  It won't load another round from the magazine (99.9%) of the time.  I have had maybe 3 or 4 times where it loaded a round just fine then the next shot it wouldn't load.  I have including a link to a video in slow mo.  https://streamable.com/fmv5fb

The best shot of the bolt is around the 2:25 mark.  I am pretty sure the rifle is short stroking

 

Here are the things I have tried.

I have tried a different gas block and tube

Different rounds with different loads

Different mags

Headspace checks out

I have not yet tried:

Different weight buffer or spring.

I have searched for a ligher or shorter spring and I have been unsuccesfull in finding a lighter or shorter spring so any advice there would be great or other any possible fixes yall can think of?

 

 

 

[Epicersatz]

I wanted to add that the bcg has good clearance into the buffer and will go all the way in.  When I manually cycle it works fine.  I have also included a picture of the gas tube into the upper.  

Edited October 16, 2020 by Epicersatz

[Epicersatz]

I also forgot to mention.  The rifle has ~300 rounds through it.  Each time I take it out I put either Mobile 1 aero grease or marine grease I have. 

[DNP]

Did you by any chance measure the gas port diameter when you had the gas block off?

What lower parts kit did you use? 
 

You have 300 rounds through it pretty much all hand cycled (for loading anyways from the sound of it)?

[Epicersatz]

4 minutes ago, DNP said:

Did you by any chance measure the gas port diameter when you had the gas block off?

What lower parts kit did you use? 
 

You have 300 rounds through it pretty much all hand cycled (for loading anyways from the sound of it)?

I haven't measured the port myself but after speaking with the owner of X-Caliber he assured me that the gas port was drilled at .095.

I got the lower completely assembled from Aero so whatever they put in it. 

Yep.  ~295 rounds hand cycled.  I was trying to put some rounds through thinking it would start to break in and jell together.  But when I hand cycle it they load just fine and even lock on an empty mag.  Firing the gun won't lock back on empty mag normally.

[DNP]

If the gas port is truly that size, it shouldn’t be an issue. Might be worth checking just to see. There’s a few others here that will be able to help you a lot more than I can, I’m just trying to ask a few questions to have more of the info available.  It’s all Aero stuff, should be playing well together.  Lubed up like crazy, right?  These guns do like to be a little wet. It’s going to be something simple - I’m sure of it. 

[Epicersatz]

4 minutes ago, DNP said:

If the gas port is truly that size, it shouldn’t be an issue. Might be worth checking just to see. There’s a few others here that will be able to help you a lot more than I can, I’m just trying to ask a few questions to have more of the info available.  It’s all Aero stuff, should be playing well together.  Lubed up like crazy, right?  These guns do like to be a little wet. It’s going to be something simple - I’m sure of it. 

Yep! I was in the process of cleaning it when i posted that picture but wanted to snap that pic based on the pinned threads in this topic of things to check first.  But yeah normally use Mobil 1, shell aero grease, or marine grease when I go out.  I am pretty positive based on the video the BCG is not coming back far enough and if I need to drill out the gas port I can but where I am I do not know any gunsmiths who can do that and I don't trust myself enough to do it.  

Edited October 16, 2020 by Epicersatz

[DNP]

Drilling the gas port is easy if it comes to that. There is a thread from the last couple days in the general section where they were walking someone through it. My guess is someone will ask a little more about the buffer and tube dimensions. Length of buffer and depth if the tube, but if it’s easy enough to do it...I would check the gas port size when you get a chance. Numbered drill bits make for easy approximations. 

Edited October 16, 2020 by DNP

[Epicersatz]

I can go ahead and answer some of those questions.  The overall length of the tube is 9 and 7/8th inch, if I include the small extension where you screw in the stock its 10 inches. The depth or internal length is 9 and 1/16th inch.  

The spring is just a standard aero 308 spring, i was incorrect in the length in my first post.  Its 11.25 inches and I believe 32 or 33 coils.  

[edgecrusher]

Buffer length too, even though rifle stuff is pretty straight forward. I’m wondering about the double extractor bs too

[jtallen83]

8 hours ago, Epicersatz said:

I haven't measured the port myself but after speaking with the owner of X-Caliber he assured me that the gas port was drilled at .095.

Just as well check that one off the list in person and get a measurement.

[Ravenworks]

Something really simple,clean your BCG throughly, get ALL the grease off it and oil it.

 

[Epicersatz]

58 minutes ago, edgecrusher said:

Buffer length too, even though rifle stuff is pretty straight forward. I’m wondering about the double extractor bs too

The buffer is 5 and 1/4th inches long.

Here is a picture of the bolt with double extractors springs.  Sorry I thought i put extractor springs in that post.  Its been one of those days.

[Armed Eye Doc]

Looking at the man who has the science figured out on AR buffer systems heavybuffers.com, it may be that your spring is too short.  Rifle length buffers need a spring that is 13.75 inches with 34 coils.

Edited October 17, 2020 by Armed Eye Doc

[98Z5V]

Rifle recoil system, so your buffer OAL is close enough to 5.200" long, so that's okay.  9 1/16" for an internal depth inside the receiver extension is WAY too short - Rifle Receiver Extensions are 9 11/16" internal depth.  Double check that number/depth.

Get rid of the spring, and run an Armalite EA1095 spring in there.  Quality spring that you don't have to guess about, and it's proven.

I think your gas port is too small in that barrel.  They might say it's 0.095", but I wouldn't trust what they say.  You'll need 0.090"~0.095" to run a rifle gas 18" barrel, if your gas block journal size is 0.750". 

You're running the A2 stock setup, if you're referencing the 5/8" long spacer for the end of the extension, before you put the stock on there.  Make sure the buttstock screw isn't too long, and protruding inside the receiver extension, when installed.  That'll stop you right in your tracks, if it's sticking into that extension, on the inside.

Edited October 17, 2020 by 98Z5V

[edgecrusher]

This ^^. Those square faced ejectors aren’t helping anything either but you haven’t mention extraction issues so....

[98Z5V]

18 hours ago, Epicersatz said:

 I have including a link to a video in slow mo.  https://streamable.com/fmv5fb

There's a bunch going on in that video that needs to change.

1.  Get your left hand off the front of that magazine, and stop pulling back on it.  That does nothing but tilt your mag forward, and point bullets downward, to the extent that it can move in the magwell.  The handguard is there, for your left hand - not the magazine.

2.  Shoot with the tip - TIP -of your trigger finger.  You have that big bugger-hook so deep in the trigger, - you're shooting that thing with the second digit. Don't do that. "Sink more finger on that trigger" works with pistols in some circumstances, but it doesn't work with something that you're building and using as a precision-type rifle.

3.  You're jerking the trigger.  As soon as that round goes off, you're trigger finger is FLYING out of that trigger guard.  Yes, even in slo-mo.  You fire, and hold the trigger to the rear, throughout the recoil cycle of the weapon, until the weapon settles itself AFTER recoil.  Then, you release the trigger, and you'll hear the "metallic click" of the disconnector releasing the hammer.  If you DON'T follow that process, you'll never, ever be able to check your Natural Point Of Aim correctly.  

4.  Your scope is too far forward, and your head is too far back on that stock. Most modern scopes have an eye relieve that's around 3".  That scope is mounted easily 2" further forward than it should be, and in your first shot, I can't even see your head in the video.  Where's your head?  Gotta be more than 6" from that scope eyepiece.  If I'm looking at the markings on the right side of that scope correctly, that's a Trijicon scope. 

Just observances from watching your video.  Sign up for, and attend an AppleSeed Shoot.  They're everywhere in the country, every state, and you'll learn a TON about marksmanship fundamentals.  Even if it doesn't have anything to do with the malfunction you're having, you need to change alot of things that you're doing with the way you're firing.  There's alot that needs fixed there.  If it never gets fixed, and you don't change it, then every rifle that you try to fire accurately, is only going to disappoint you.  And it won't be the fault of the rifle.

Look into what @edgecrusher stated about the square-faced ejectors...   They don't like to feed rounds that are coming from the right side of the magazine, in that double-stack mag.

 

[Epicersatz]

3 hours ago, 98Z5V said:

There's a bunch going on in that video that needs to change.

1.  Get your left hand off the front of that magazine, and stop pulling back on it.  That does nothing but tilt your mag forward, and point bullets downward, to the extent that it can move in the magwell.  The handguard is there, for your left hand - not the magazine.

2.  Shoot with the tip - TIP -of your trigger finger.  You have that big bugger-hook so deep in the trigger, - you're shooting that thing with the second digit. Don't do that. "Sink more finger on that trigger" works with pistols in some circumstances, but it doesn't work with something that you're building and using as a precision-type rifle.

3.  You're jerking the trigger.  As soon as that round goes off, you're trigger finger is FLYING out of that trigger guard.  Yes, even in slo-mo.  You fire, and hold the trigger to the rear, throughout the recoil cycle of the weapon, until the weapon settles itself AFTER recoil.  Then, you release the trigger, and you'll hear the "metallic click" of the disconnector releasing the hammer.  If you DON'T follow that process, you'll never, ever be able to check your Natural Point Of Aim correctly.  

4.  Your scope is too far forward, and your head is too far back on that stock. Most modern scopes have an eye relieve that's around 3".  That scope is mounted easily 2" further forward than it should be, and in your first shot, I can't even see your head in the video.  Where's your head?  Gotta be more than 6" from that scope eyepiece.  If I'm looking at the markings on the right side of that scope correctly, that's a Trijicon scope. 

Just observances from watching your video.  Sign up for, and attend an AppleSeed Shoot.  They're everywhere in the country, every state, and you'll learn a TON about marksmanship fundamentals.  Even if it doesn't have anything to do with the malfunction you're having, you need to change alot of things th at you're doing with the way you're firing.  There's alot that needs fixed there.  If it never gets fixed, and you don't change it, then every rifle that you try to fire accurately, is only going to disappoint you.  And it won't be the fault of the rifle.

Look into what @edgecrusher stated about the square-faced ejectors...   They don't like to feed rounds that are coming from the right side of the magazine, in that double-stack mag.

 

To answer 1 through 3 - I am not very experienced at all with rifles so thank you and notated.  I have a couple of AR15s but don't shoot my rifles very much.  I will add that to your number 1 I normally don't rest of my hand there, it does have a bipod so my hand is normally not on the rifle (basically saying that the rifle still has the feed issue regardless)

Number 4 I had taken the scope and handguard off to check the gas block at the range and used the scope mount to line up the rails on the handguard and upper till i could get back home.  I do normally have the scope closer to the back of the rifle. 

 

@edgecrusher and @98Z5V Being still new the platform with AR/LRs can I just get a new extractor and springs and work with the bolt? At this point is it even a worry since I haven't had issues with extractions? 

 

I am going out to the store in a bit to get some tools so I will post some more pictures of more measurements when I get back!

[Epicersatz]

Ok so after some more measurements:

My caliper couldn't get in the gas port well so I turned to a drill bit and a 5/64 fit all the way in the hole but a 3/32 was just a tad big to get in.  When I put the calipers above the hole I was estimating .089. 

 

Here is a pic of the buffer tube. 

I am starting to go with the fact the gas port might be a tad bit undersized.

[Epicersatz]

I also wanted to add this description and picture and not sure if it is relevant.  Upon closer inspection of the barrel and gas port it seems there is an insert or collar in the gas port hole.

[DNP]

No, that is carbon built up around the hole. It seals off the open space. The hole in the gas block is bigger that the hole in the barrel. That will scrub off if you clean it. When you put things back on, it will take several rounds to seal that back up. 

[Epicersatz]

56 minutes ago, DNP said:

No, that is carbon built up around the hole. It seals off the open space. The hole in the gas block is bigger that the hole in the barrel. That will scrub off if you clean it. When you put things back on, it will take several rounds to seal that back up. 

def a metal sleeve of some kind in the hole.  not sure if this is normal.  just an observation.

[Radioactive]

28 minutes ago, Epicersatz said:

def a metal sleeve of some kind in the hole.  not sure if this is normal.  just an observation.

I doubt it - they all look like that when the gas block is removed unless no rounds fired. I have never heard of sleeving the gas port. I’d be real surprised.

[shooterrex]

Those are dual ejectors NOT extractors.

KAK sells the ejectors that are rounded on top.

[DNP]

1 hour ago, Epicersatz said:

def a metal sleeve of some kind in the hole.  not sure if this is normal.  just an observation.

Clean it up and take another pic. I’d be really surprised to see something like that and would immediately return that barrel as there is zero reason to have a sleeve. Doesn’t happen.