Failure to eject/extract

[Scott76]

FAR. 
 

I’m in Kenosha. 

[unforgiven]

I worked for Martin Peterson in Kenosha.

[Scott76]

1 hour ago, unforgiven said:

I worked for Martin Peterson in Kenosha.

Small world!

[Radioactive]

2 hours ago, Scott76 said:

FAR. 
 

I’m in Kenosha. 

I got my ass kicked in a Kenosha bar back in 80 while I was stationed in great lakes

there was actually 3 of us that took a whoopin but we were seriously out numbered

got arrested up in Fondulac

good times

 

 

[Scott76]

Lol. It used to be a pretty rough town back in the day. It’s actually growing like crazy and the downtown area is seriously nice now. I’ve been here for 20 years and I’ve seen some huge changes in that time. Love my town. 

[98Z5V]

On 1/17/2020 at 1:43 PM, Scott76 said:

Gun specs:

Faxon 20" pencil barrel

That's a high quality barrel - we're working with 20" Rifle gas and 0.750" gas block diameter.

7 hours ago, Scott76 said:

I may have not said this clearly. 4.5 turns IS wide open. Zero turns out is completely restricted, the port is totally closed. 4.5 turns it is functioning like a standard non adjustable gas block.

I didn't know that 4.5 turns out was wide open on that gas block.  I never use adjustable gas blocks, so I don't know what the settings are on any of them.

20" Rifle gas with a .750 journal area is gonna be about the same dwell time as a 16" Midlength gas with a .750" journal.  Pretty close.  You need 0.080~0.085" to properly run a 16"Midlength .750 journal-barrel, so you'll need a gas port diameter close to a range of 0.080~0.085".  What's the gas port diameter that Faxon drilled in that one that you have?

[Scott76]

Just checked their website, it doesn’t say. I could take it apart and put a mic on it to check. 
 

I’m somewhat second guessing my choice in running the adjustable gas block, but the long term plan was to run a suppressor so my thought was that was the way to go. 

[unforgiven]

2 hours ago, Radioactive said:

I got my ass kicked in a Kenosha bar back in 80 while I was stationed in great lakes

there was actually 3 of us that took a whoopin but we were seriously out numbered

got arrested up in Fondulac

good times

 

 

I had the privilege to help build the barracks and the place for the parents of the graduate's at Great Lakes .

Edited January 19, 2020 by unforgiven
Bad hands

[98Z5V]

24 minutes ago, Scott76 said:

Just checked their website, it doesn’t say. I could take it apart and put a mic on it to check. 
 

I’m somewhat second guessing my choice in running the adjustable gas block, but the long term plan was to run a suppressor so my thought was that was the way to go. 

I hit the website right away, and didn't find it.

Adjustable gas for suppressed/unsuppressed use is smart.    One of these days, I'll add suppressors into the mix, and it's gonna cost me bigtime...

[Scott76]

I hear ya man.  Silencershop had the Deadair Nomad 30 back in stock and I had it all loaded up in the cart. Then I thought about spending almost a grand on something I likely won’t see for 11 months, and I bought more hunting clothes instead lol. 
 

I really should get one though, I have five rifles I could use it on. 

[Steve]

I bought a new Smith & Wesson MP 10 in .308, and have had the same failure to eject Problem.  This is my first 30 cal AR So this is all a learning curve fo me. 
 I shot 20 rounds of Remington Core Lok 150 gr without any flaws. The 3rd magazine started ok, then I started having failure to eject,  failure to load and failure to lock after the last round. I talked to the dealer and he told me that he has always experienced the need for a break in period on his .308s. 
I went home, cleaned, oiled the BCG and the counter bore/ bore. (Wet) Back to the range, 20 rounds of Winchester 180 gr shot a nice group. Then same problems on the next 10 rounds. I called S&W, and with out question they sent me a shipping label. I decided to try one more time at the range. Another 40 rounds still had similar issues. So I have fired a little more than 120 rounds through my AR10 with about a 40% failure to eject, feed and lock after last round. I am going to send it to S&W and let them determine what the problem is.
Side note: I have used 4 different MagPul a one HexMag Magazines.  

[Scott76]

Guys bringing this old thread back. I have lubed the poop out of the gun, and ran about 50 more rounds through it, this time using FMJ. I’m still having failure to eject issues, but not as frequently. I’m considering the springco enhanced ejector springs or maybe the KAK Industries double ejector bolt. Thoughts?  The rest of the gun is fantastic, id just like for it to run correctly. 

[sketch]

did you get a gas port measurement? 

[Scott76]

15 hours ago, sketch said:

did you get a gas port measurement? 

I have not. I actually forgot that was an area of concern until I went out and shot it again and re read this thread. 

[Scott76]

On 4/24/2020 at 6:49 PM, sketch said:

did you get a gas port measurement? 

Okay got it torn down and measured. Port on the barrel is 85thou, port in the block is 125 thou. 

[sketch]

thats not bad, there is room to grow for sure. I've gone to .094 on a barrel I had some trouble with mixed with other issues. @98Z5V is my guru. 👍🏻

[Scott76]

I took the bolt apart and both extractor springs and the ejector spring look fine. I’m somewhat stumped at this point. 
 

I have springco ‘extra power’ ejector and extractor springs sitting here. Wonder if I should give those a run.  Sucks I feel like I’m just throwing parts at it now and hoping for the best, and that’s not how I work on poop. 

Edited April 27, 2020 by Scott76

[98Z5V]

4 hours ago, Scott76 said:

Okay got it torn down and measured. Port on the barrel is 85thou, port in the block is 125 thou. 

Bump it up to 0.095" - your dwell time is 6.875".  It will solve your problems, completely.  0.093"~0.096" will work.   I never should have compared it directly to a 16" midlength barrel, just on dwell time alone.  My fuk-up, there.  You need more gas port diameter on that gun. 

Edited April 28, 2020 by 98Z5V

[Scott76]

12 hours ago, 98Z5V said:

Bump it up to 0.095" - your dwell time is 6.875".  It will solve your problems, completely.  0.093"~0.096" will work.   I never should have compared it directly to a 16" midlength barrel, just on dwell time alone.  My fuk-up, there.  You need more gas port diameter on that gun. 

I’m curious - would that have the net effect of delivering more gas, sooner, to the gas key?  So in effect, my gun is behaving under gassed?

[98Z5V]

12 hours ago, Scott76 said:

I’m curious - would that have the net effect of delivering more gas, sooner, to the gas key?  So in effect, my gun is behaving under gassed?

Your gas port is too small.  It can't deliver enough gas to cycle the weapon with proper timing. 

Let's think about swimming underwater for a second.  You're constrained underwater, and you cannot break the surface.  You get to breathe through a tube, and you remain below the surface of the water.  Do you think you can get a lung-full of air better through a McDonalds straw, or a 1" diameter piece of PVC pipe? 

Your gas port is choking your gun - because the gas can't get there through that small port.  With the proper timing that it was designed around.

This whole .308AR gun system is a fight between two systems that MUST be balanced.  Gas System and Recoil System.  If one of them is even a little out of whack - your gun doesn't work.  Or, it works sometimes, but not all the time.

Your gas port is too small.

[Scott76]

I’m just trying to educate myself man.  I’ve spent a few hours scouring dwell time and gas issues in an effort to be better informed. I’m not doubting your conclusions or advise in any way.  It does make me wonder why a reputable barrel manufacturer would build a barrel that way if it’s a known issue.  It’s not like it takes extra setup or fixture time to drill the port to a workable spec.  

[Albroswift]

@Scott76Just curious, did you try cranking the gas block closed until the bolt wouldn't lock back? I think I saw in your original post that the BCG always locked back. It's possible some of the blow by type AGB's will not vent enough gas to make much of a difference in 308's. I have one on a midlength and that seems to be the case. 

EDIT Bleed-off, Superlative Arms is the one I'm referring to.

Edited April 29, 2020 by Albroswift

[98Z5V]

37 minutes ago, Scott76 said:

I’m just trying to educate myself man.  I’ve spent a few hours scouring dwell time and gas issues in an effort to be better informed. I’m not doubting your conclusions or advise in any way.  It does make me wonder why a reputable barrel manufacturer would build a barrel that way if it’s a known issue.  It’s not like it takes extra setup or fixture time to drill the port to a workable spec.  

Tons of companies making tons of parts, and got into the Big AR Game, way late.  Some companies followed other patterns, very few companies followed Armalite's pattern - probably for fear of pattern infringement/lawsuits.  The original pattern works - and yet I don't own a single Armalite complete AR-10, at all.  I just watched what they did, which works, flawlessly.  Other companies that started making these (DPMS, RRA, Bushmaster) made compromises to the original system, to stave off those problems.

NOW, you have every company making .308ARs - most followed the DPMS platform.  Many of them don't even make in-spec parts in the first place.  Toss in the aftermarket companies that don't even make complete rifles, just components, only - making a guerss at what they need to do - and it gets even worse.  Some component companies have their shiit together - most don't.

I won't bullshiit you on gas port numbers.  If I suggest you drill something, and it completely doesn't work on your barrel - I'll buy your barrel from you and make it work. 

Edited April 29, 2020 by 98Z5V

[Scott76]

14 minutes ago, 98Z5V said:

Tons of companies making tons of parts, and got into the Big AR Game, way late.  Some companies followed other patterns, very few companies followed Armalite's pattern - probably for fear of pattern infringement/lawsuits.  The original pattern works - and yet I don't own a single Armalite complete AR-10, at all.  I just watched what they did, which works, flawlessly.  Other companies that started making these (DPMS, RRA, Bushmaster) made compromises to the original system, to stave off those problems.

NOW, you have every company making .308ARs - most followed the DPMS platform.  Many of them don't even make in-spec parts in the first place.  Toss in the aftermarket companies that don't even make complete rifles, just components, only - making a guerss at what they need to do - and it gets even worse.  Some component companies have their shiit together - most don't.

I won't bullshiit you on gas port numbers.  If I suggest you drill something, and it completely doesn't work on your barrel - I'll buy your barrel from you and make it work. 

Can’t argue with that. Strong point. 

[Scott76]

48 minutes ago, Albroswift said:

@Scott76Just curious, did you try cranking the gas block closed until the bolt wouldn't lock back? I think I saw in your original post that the BCG always locked back. It's possible some of the blow by type AGB's will not vent enough gas to make much of a difference in 308's. I have one on a midlength and that seems to be the case. 

EDIT Bleed-off, Superlative Arms is the one I'm referring to.

I was 9 clicks out from max blow by and it still locked back.  I’ve since returned it to max flow and am trying to solve the issue before I complicate poop. 

Edited April 29, 2020 by Scott76