New AR10 won’t cycle

[G2fspro]

I just built my AR-308 and went to fire it yesterday and it would either not cycle or I’d have a FTE. I adjusted the gas block several times and had no luck. When standing in front of the rifle, I turned it clockwise all of the way and then 18 clicks (4.5 rotations) counter clockwise.

 

I looked at it when I got home and I did not see any visible issues on the feed ramps or bolt. 

 

Here are a few things I did notice:

 

1. When I pushed the bolt in to seat it, it required a bit more force than an AR15. Not much but just noticeably more.
2. It will cycle fine manually and the bolt will lock back when you manually cycle the last round from the mag.
3. After manually cycling, I looked at the cartridge and noticed that they were being scratched during the manual cycling.

 

I had the barrel and bolt checked for headspace by a a gunsmith prior to assembly and had them mount the gas block since I know Superlative can be tricky. I also removed one of the o-rings on the extractor as it’s common that causes issues on the Aero bcg.

 

Upper: Aero M5

Lower: Aero M5

BCG: Aero M5 NB

Barrel: Wilson Combat Recon 16”

Gas Tube: Wilson Combat Intermediate

Gas Block: Superlative ADJ bleed off.750

Buffer Tube: KAW Valley AR10 6-pos

Buffer Spring: KAW Valley KVP AR-10/XP Stainless Steel Recoil Spring

Buffer: KAW Valley 5.6 oz Stainless Steel Tungsten Heavy Buffer

Trigger: Rise Armament RA-242

 

I am shooting a regular muzzle break, non-suppressed. I’ve built 100s of AR15s without fail but I know the AR10 is a different animal.  I’m just at a loss on what my issue could be.

[Armed Eye Doc]

A couple of things to look at first:

How much lube did you use when shooting?  These tend to want a lot more lube than AR15s during break in.

Can you take a picture of where the end of your gas tube sits relative to the cutout (up through the mag well)?

What is the size of your gas port?  Many of these barrels (including Wilson Combat) have a small gas port causing it to be undergassed regardless of how much you open the gas block.

[98Z5V]

When there's a chance, can a Mod/Admin move this to the Build Section?

[Matt.Cross]

On 3/6/2022 at 11:59 AM, 98Z5V said:

When there's a chance, can a Mod/Admin move this to the Build Section?

Done. Thanks for the heads up!

[G2fspro]

I was very generous with lube as it was a new build. I used Amsoil gun lube. I was using M80 ball ammo. The gas tube was almost to the edge of the cam pin cutout so I pulled the handguard off and noticed the gas block was seated flush with the collar. I spaced it out using a thing credit card since Superlative recommended an 0.025 space. I’ll check it with a feeler gauge to be certain. I’m sure this did not help with the cycling. I also found that sometimes Wilson barrels need gas ports enlarged so I checked and I could fit a 1/16 bit in the port hole but not a 5/64. I was told by a member the gas port should be 0.86.
 

I called Aero today before I took it apart and they advised my spring May be too heavy and my buffer may be too heavy as well.
 

Thoughts?

[jtallen83]

Just now, G2fspro said:

Thoughts?

That Aero customer service isn't such a great place for info on large frame AR's is the first thing that came to mind. I don't know that spring but your buffer is right.

You can slide the gas block out of the way to check alignment, there will be a shadow where the larger gas block hole sits over the port in the barrel. 

How familiar are you with the Superlative gas block as far as the settings go? I found it a pain with the two in one system, couldn't get the bleed off side to stop function on a 308 so that made it just a common restrictive gas block. 

Put the O ring back or get a good known quality spring set for the extractor, seems like Wilson Combat had some for sale lately. 

[G2fspro]

3 minutes ago, jtallen83 said:

That Aero customer service isn't such a great place for info on large frame AR's is the first thing that came to mind. I don't know that spring but your buffer is right.

You can slide the gas block out of the way to check alignment, there will be a shadow where the larger gas block hole sits over the port in the barrel. 

How familiar are you with the Superlative gas block as far as the settings go? I found it a pain with the two in one system, couldn't get the bleed off side to stop function on a 308 so that made it just a common restrictive gas block. 

Put the O ring back or get a good known quality spring set for the extractor, seems like Wilson Combat had some for sale lately. 

This is my first time using the Superlative block. I have it adjusted to fully open right now but not into bleed off. The spring came with the KAW Valley buffer tube set. I used it based on the great reviews it had with Aero 308s so I took what they said with a grain of salt. 

[98Z5V]

29 minutes ago, G2fspro said:

I called Aero today before I took it apart and they advised my spring May be too heavy and my buffer may be too heavy as well.
 

Thoughts?

Rubbish.   They don't know how WC is making their barrels, anyway.  Aero sends out light recoil systems, and makes gas ports smaller to compensate for this - WC does the same on some barrels, but not all.  Both my .260 Rem barrels had to go up in diameter, but the .338 Fed barrel was excellent.

WC's Intermediate gas system is slightly longer then midlength gas.  What I know for a fact:  18" midlength gas barrels with a 0.750" gas block journal diameter require a gas port diameter that's between 0.080"~0.085".  You have a shorter 16" barrel, and a longer gas system, so that equals less dwell time.  Your gas port will need to be smaller than what I listed above.  However, you have an adjustable gas block , and you can always adjust the pressure down.  If that was my barrel, I'd be going for something in the range of 0.075"~0.080" for a gas port diameter. 

On another note, always, always start a new adjustable gas block wide open.  Can't stress that enough. 

Edited March 9, 2022 by 98Z5V

[G2fspro]

14 hours ago, 98Z5V said:

Rubbish.   They don't know how WC is making their barrels, anyway.  Aero sends out light recoil systems, and makes gas ports smaller to compensate for this - WC does the same on some barrels, but not all.  Both my .260 Rem barrels had to go up in diameter, but the .338 Fed barrel was excellent.

WC's Intermediate gas system is slightly longer then midlength gas.  What I know for a fact:  18" midlength gas barrels with a 0.750" gas block journal diameter require a gas port diameter that's between 0.080"~0.085".  You have a shorter 16" barrel, and a longer gas system, so that equals less dwell time.  Your gas port will need to be smaller than what I listed above.  However, you have an adjustable gas block , and you can always adjust the pressure down.  If that was my barrel, I'd be going for something in the range of 0.075"~0.080" for a gas port diameter. 

On another note, always, always start a new adjustable gas block wide open.  Can't stress that enough. 

Thank you sir, I appreciate it. I’ll report back.