I am stumped - Aero M5 308

[Houghtontaylor]

Alright boys.. let's see if we can solve this together. Because I cannot and it is driving me up a wall. 

 

The build is as follows; I have two of everything below as I built one for my father and one for myself. both do not work as of now.

Aero M5 upper and lower

Wilson combat 20" barrel w/ rifle length gas system (Armalite @ 15.5")

Odin works adjustable gas block 0.875

Aero Rifle length buffer w/ standard weight buffer and spring

Aero NiB BCG and Nitride coated

Magpul 25 and 10 round magazine

1x muzzle break (GSL 7.62 two port break)

All major brands of ammo used

 

 

Bear with me... The Rifle came together beautifully. Initial shots were not cycling the action. The rifle appeared to be under-gassed since bolt would not lock back, extract the round or cycle the next round. Gas tube alignment was checked and confirmed to be correct both left and right as well as forward and back. Gas block was disassembled and confirmed to be in the completely open position. Rifle would not cycle next round. Gas tube and gas block was sealed with blue loctite in case there was a gas leak taking care not to plug holes. compressed air through the system confirmed that it was not obstructed. same problem. Carrier key appears to be properly staked. The BCG stands upright on the table when set on the bolt face and the 3 gas rings appear to be in order. Two different aero BCGs were used in my troubleshooting. The ar15 rifle length gas tube was swapped out with an AR10 armalite rifle length gas tube that is slightly longer. Gas tube now goes 2/3rds of the way past the center of the oval when looking into the upper receiver as opposed to 1/3rd with the ar15 rifle length gas tube. The rifle cycles intermittently. some shots appear to short stroke but get caught on the front of the ejection port and crushed as the bolt comes forward seemingly being a failure to eject. Other shots appears to be a failure to extract with the spent casing stove piping while the live round is jammed between the BCG and the feed ramps. Since I have two nearly identical rifles I was able to swap parts back and forth in order to trouble shoot. I was also able to borrow parts from my Aero 6.5 build that runs without issue. I have a JP silent capture buffer system that I installed. No change. The rifle does not cycle. I had noticed a small burr on the extractor face of the NiB BCG likely from when I mortared the rifle to dislodge a spent casing when gas block was closed 100%. NiB BCG was swapped out with an aero nitride BCG with no change in pattern. Thinking there was some bad juju with that upper I removed the muzzle break from the #1 upper and installed on the #2, somewhat identical upper that used a nitride aero BCG instead of a NiB one. 25 round Magpul mag loaded with an assortment of high $ ammunition all failed to cycle properly. I then tried the 10rnd magazine and again, did not cycle (spent shell stove pipe and live round jammed)

I then took the #1 upper with just threads at the end. It would not cycle with the 25 round Magpul magazine but would cycle the 10 round magazine. I swapped the Nitride BCG over to the #2 and shot the same ammo with the 10 and magazine. Only difference is the presence of the muzzle break. Rifle would not cycle.

I consider myself to be a patient person and somewhat competent when it comes to these things. But this just perplexes me. My thoughts right now are on a few things. Here they are from most likely to least likely;

1. It appears to like the 10 round magazine over the 25 round one. Why, I do not know

2. muzzle device. Since the rifle seems to cycle only the 10rnd magazine without a muzzle device, it leads me to believe the muzzle break is at least part to blame. I find this strange since I would imagine breaks to add back pressure, not decrease it. GSL was found by the guy who founded Gemtech. I cannot imagine this to be my issue since it is well designed and in my opinion unlikely to cause these issues. 

3. Adjustable gas block: I have not noticed any presence of carbon after shooting that would indicate a leak in the block. I am unfamiliar with Odin works and their reputation. My thoughts are there could be a leak somewhere in the block itself that is decreasing the total gas in the system. I have yet to find evidence of this but its on my list. 

4. Dwell time: This is an 20" barrel with a rifle length gas system. I am unsure of the port size. I trust that the engineers over at WC thought about dwell time and bored out the gas port to the adequate dimensions. But, since I cannot rule it out, it is on my list. 

 

I really do not want to take this to a gunsmith for the sake of mostly my pride. It just does not make any sense to me. I have a mix of quality parts, all of which were unable to yield an operational/ reliable rifle. I knew 308 gassers were finicky but this is a new level for me. As far as next steps. I am thinking about getting a non adjustable gas block and different magazines. I did not want to run a non adjustable gas block since the rifle will be suppressed. Oh and the rifle runs 80% while suppressed but will not run properly unsuppressed. I assume all the back pressure from the can just beats the rifle into submission. Anyhow, If any of you have any thoughts or ideas, please. I am all ears. 

 

[shooterrex]

A couple of thoughts.

Drill out the gas port. You have an adjustable gas block so you can close it down if your getting too much gas at a latter date.

Till you get the guns working don't use change more than one thing at a time. How do you know what made things work or worse if you are changing more than one thing at a time.

Dip your BCG in a pan of Mobile One motor oil overnight. Then just wipe off the bolt face and shoot it.

Till you get it locking back just load one round at a time in the magazine.

Are you sure that you have a 308 buffer and recoil spring.

[edgecrusher]

I bet your gas port is under sized. Please check the diameter. Also, weigh and measure your buffer and spring, let’s just verify those are correct. Inner diameter of the buffer tube as well.

[Houghtontaylor]

Shooterrex, apologies I didn't make this clearer. Every operation that was done was test fired in between to make sure only one "system" was tested at one time. 

There is approximately 6 3/4 inches from the gas port to the muzzle with a port size of 0.085". According to some tables online for AR10 gas port sizing. This port size is toward the minimum recommended size. I will increase the gas port to 0.093. BCG is soaking as we speak. 

 

Edge Crusher, The buffer weight is 5.4 oz and 5 1/4" long.  The spring length is 12 3/4". I tested a JP silent capture buffer system for .308 with spacer and there was no change. 

 

I am starting to think this is a gas port size issue. Why on Earth would WC build a barrel with an undersized gas port. Are the vast majority of 308 gassers over gassed?

I read another resource about gas port sizing and for a 20 inch barrel they recommend: Min 0.093" and max 0.1". Well my 0.085 is FAR under what is recommended. 

Edited January 17, 2022 by Houghtontaylor

[jtallen83]

8 hours ago, Houghtontaylor said:

Why on Earth would WC build a barrel with an undersized gas port.

To make it work with a 3.5 ounce buffer system, all kinds of compromises are made by manufacturers in this platform, including bullschit in-between gas port locations. 

Could be you need more rounds, mate surfaces, seal gas leaks, break in you know. 

[Armed Eye Doc]

9 hours ago, Houghtontaylor said:

I read another resource about gas port sizing and for a 20 inch barrel they recommend: Min 0.093" and max 0.1". Well my 0.085 is FAR under what is recommended. 

I would say that you will likely need to drill your gas port up a bit.  The difference in size recommendations depends, first, on the barrel length and gas length and, second, the diameter of your barrel at the gas port.  A bull barrel needs a different gas port size than a pencil barrel.

If you list the diameter of your gas block, @98Z5V can calculate what size gas port you should need.

[98Z5V]

20 hours ago, Houghtontaylor said:

Alright boys.. let's see if we can solve this together. Because I cannot and it is driving me up a wall. 

 

The build is as follows; I have two of everything below as I built one for my father and one for myself. both do not work as of now.

Aero M5 upper and lower

Wilson combat 20" barrel w/ rifle length gas system (Armalite @ 15.5")

Odin works adjustable gas block 0.875

Aero Rifle length buffer w/ standard weight buffer and spring

Aero NiB BCG and Nitride coated

Magpul 25 and 10 round magazine

1x muzzle break (GSL 7.62 two port break)

All major brands of ammo used

 

 

Bear with me... The Rifle came together beautifully. Initial shots were not cycling the action. The rifle appeared to be under-gassed since bolt would not lock back, extract the round or cycle the next round. Gas tube alignment was checked and confirmed to be correct both left and right as well as forward and back. Gas block was disassembled and confirmed to be in the completely open position. Rifle would not cycle next round. Gas tube and gas block was sealed with blue loctite in case there was a gas leak taking care not to plug holes. compressed air through the system confirmed that it was not obstructed. same problem. Carrier key appears to be properly staked. The BCG stands upright on the table when set on the bolt face and the 3 gas rings appear to be in order. Two different aero BCGs were used in my troubleshooting. The ar15 rifle length gas tube was swapped out with an AR10 armalite rifle length gas tube that is slightly longer. Gas tube now goes 2/3rds of the way past the center of the oval when looking into the upper receiver as opposed to 1/3rd with the ar15 rifle length gas tube. The rifle cycles intermittently. some shots appear to short stroke but get caught on the front of the ejection port and crushed as the bolt comes forward seemingly being a failure to eject. Other shots appears to be a failure to extract with the spent casing stove piping while the live round is jammed between the BCG and the feed ramps. Since I have two nearly identical rifles I was able to swap parts back and forth in order to trouble shoot. I was also able to borrow parts from my Aero 6.5 build that runs without issue. I have a JP silent capture buffer system that I installed. No change. The rifle does not cycle. I had noticed a small burr on the extractor face of the NiB BCG likely from when I mortared the rifle to dislodge a spent casing when gas block was closed 100%. NiB BCG was swapped out with an aero nitride BCG with no change in pattern. Thinking there was some bad juju with that upper I removed the muzzle break from the #1 upper and installed on the #2, somewhat identical upper that used a nitride aero BCG instead of a NiB one. 25 round Magpul mag loaded with an assortment of high $ ammunition all failed to cycle properly. I then tried the 10rnd magazine and again, did not cycle (spent shell stove pipe and live round jammed)

I then took the #1 upper with just threads at the end. It would not cycle with the 25 round Magpul magazine but would cycle the 10 round magazine. I swapped the Nitride BCG over to the #2 and shot the same ammo with the 10 and magazine. Only difference is the presence of the muzzle break. Rifle would not cycle.

I consider myself to be a patient person and somewhat competent when it comes to these things. But this just perplexes me. My thoughts right now are on a few things. Here they are from most likely to least likely;

1. It appears to like the 10 round magazine over the 25 round one. Why, I do not know

2. muzzle device. Since the rifle seems to cycle only the 10rnd magazine without a muzzle device, it leads me to believe the muzzle break is at least part to blame. I find this strange since I would imagine breaks to add back pressure, not decrease it. GSL was found by the guy who founded Gemtech. I cannot imagine this to be my issue since it is well designed and in my opinion unlikely to cause these issues. 

3. Adjustable gas block: I have not noticed any presence of carbon after shooting that would indicate a leak in the block. I am unfamiliar with Odin works and their reputation. My thoughts are there could be a leak somewhere in the block itself that is decreasing the total gas in the system. I have yet to find evidence of this but its on my list. 

4. Dwell time: This is an 20" barrel with a rifle length gas system. I am unsure of the port size. I trust that the engineers over at WC thought about dwell time and bored out the gas port to the adequate dimensions. But, since I cannot rule it out, it is on my list. 

 

I really do not want to take this to a gunsmith for the sake of mostly my pride. It just does not make any sense to me. I have a mix of quality parts, all of which were unable to yield an operational/ reliable rifle. I knew 308 gassers were finicky but this is a new level for me. As far as next steps. I am thinking about getting a non adjustable gas block and different magazines. I did not want to run a non adjustable gas block since the rifle will be suppressed. Oh and the rifle runs 80% while suppressed but will not run properly unsuppressed. I assume all the back pressure from the can just beats the rifle into submission. Anyhow, If any of you have any thoughts or ideas, please. I am all ears. 

 

Rifle buffer systems in both guns.  The extensions will be in spec for internal depth, no way around that (internal depth on a rifle extension is 9 11/16").  No manufacturer fuks that up, but it's worth checking.

Rifle buffers for .308ARs (not including RRA LAR-8s and Bushmaster BAR-10s) are 5.200 long, mand they weigh 5.4oz.  Nobody fucks that up, generally, but we've seen some length problems here recently on large-frame rifle buffers.  It's worth checking.

Call the spring shiit, right off the bat, and it's suspect, only because they can't confirm one standard or the other, and there are only two standards.  Armalite makes the EA-1095 spring, and it doesn't fail.  Sprinco makes the Red spring, and it doesn't fail.  Those are the only two springs that are of known good quality, period, that I've seen.  THere might me one or two others, but I've never used them, and verified them myself.  I have used both of the springs I listed.

Verify your recoil system first.  After that, we work on your gas system. 

For reference, read this.  I'm not dumb on what's going on here.  Baby steps, fix what's directly wrong or suspect first.  We get into the gas system next.  Check it:

 

[392heminut]

23 hours ago, jtallen83 said:

To make it work with a 3.5 ounce buffer system, all kinds of compromises are made by manufacturers in this platform,

 

His buffer is 5.4 ounces brother.

[jtallen83]

31 minutes ago, 392heminut said:

His buffer is 5.4 ounces brother.

Yep, just the only answer to his question on why they would use an undersized gas port I can come up with beyond human error.

[Unamed_]

I am curious if the M5 model needs the longer rifle (Armalite) gas tube ? 

[shooterrex]

12 minutes ago, Unamed_ said:

I am curious if the M5 model needs the longer rifle (Armalite) gas tube ? 

That all depends on where the barrel manufacturer drilled the gas port. Some seem to drill them AR-15 rifle length and some drill them AR-10 length and some drill them whever the fuk they feel like it.

[unforgiven]

I put together a .260 rifle gas .750 steel gas block with Armalite rifle gas tube,M5 upper, Toolcraft BCG, and Armalite AR-10 recoil system. Sold it never had any complaints.

[98Z5V]

2 hours ago, Unamed_ said:

I am curious if the M5 model needs the longer rifle (Armalite) gas tube ? 

You won't know until you put a gas tube in a gas block, mount it to the barrel, and put the barrel in a receiver.  If that gas tube doesn't come to the very center of the cam pin cutout in the upper receiver, at least, then it's not right.

I can talk you through the math on this, which is easy, but you still need the barrel mounted in an upper receiver.

[Houghtontaylor]

Update:

after drilling out the gas port the rifle seems to operate much better. Only was able to run 40 rounds through it with one failure. 
 

both rifles ran much smoother. I’ll probably take it up to 0.095 since I have an adjustable gas block. Such a weird concept for me. I would love to get coffee with the Wilson combat engineer and get their side. 

[98Z5V]

What's the specs on the rest of the stuff?  Fix the recoil system issues yet?  It'll work even better once you do that.

[TwoHammerTrav]

Looks like you have a low profile handguard and the Aero upper is a high profile.  Wonder if that causes any issues other than rails not lining up?

Edited September 10, 2022 by TwoHammerTrav

[98Z5V]

14 hours ago, TwoHammerTrav said:

Looks like you have a low profile handguard and the Aero upper is a high profile.  Wonder if that causes any issues other than rails not lining up?

What you've pointed out will never, ever be able to cause a functional issue in one of these rifles. 

[Black_Sheep]

FWIW my WC barrel also had an undersized gas port…