LR-308 not ejecting cartridge.

[RacerX]

Have you considered trying different ammunition?  I don't know how much faith to put in this(those with more experience will weigh in), but I saw a chart somewhere that said for a 1:10 twist (which your barrel has) that 170-220 grains was optimal.

I had a similar issue with an AR-15 style rifle, found a chart, and I'll be darned if switching from 55 grain to 77 grain didn't solve everything.

Edited August 28, 2021 by RacerX

[Rsquared]

Dunk your bolt carrier in mobil 1 (seriously). Let it soak for a while, just because. Pick it up and dry off the bolt face (not the rest of it.....let it keep dripping). Drop her in the upper and run a couple mags through it. That's what we mean when we say run it "wet". Keep that thing slinging a little oil for the first hundred or so rounds, and she'll smooth out.

If we still have issues after that, we can diagnose them one at a time.

She'll run.

[thossoma@pm.me]

I will give the BCG a good soak next time and spray it with oil as I shoot.

I noticed a pattern on my shells from the last test.  The two scratch marks on the neck of the shell. Does this mean anything or shed any light on any problem?

 

Also, when I was shooting the steel casings and the shell was ejecting, it was flying to around 1 o'clock to 2 o'clock.

Also, some of the primers look pushed out where the firing pin hit them.  Looks to be just the brass.

 

[jtallen83]

I've got a buckets of brass that look like that. You can soften some edges around the feed ramp and lessen scratches but rounds through the rifle will do the same thing. I can't tell for sure in the picture but I don't see obvious pressure signs, looks more like the crater you get when the firing pin tip is a bit under spec, the hole in the bolt over spec or even both in spec but on opposite sides of tolerance. Ejector swipe doesn't look excessive.

[98Z5V]

On 8/28/2021 at 7:10 AM, thossoma@pm.me said:

I put about 30 rounds through this trip.  Should I just use something like REM OIL while breaking her in?  And should I be spraying it into where the cartridge seats into the barrel and all over the BCG?

No, you don't want oil in the chamber.  When that spring seats that cartridge, that oil won't compress - it'll dent the hell out of the case, instead.  I'm not saying you want a bone-dry chamber, because that will never happen with a lubed up gun - some will get in there.  But you don't want to add oil into the chamber.

[thossoma@pm.me]

Got some news!  

I took some 5w30 oil and poured it into a ziploc bag and took my bcg and threw it into it over night.  I also bought an adjustable gas block https://www.midwayusa.com/product/1094240120979.

I wiped off the face of the bolt and threw it in. I adjusted the gas block all the way closed and fired shots one at a time and slowly adjusted the gas block open until the bolt locked back shooting the last round from the mag.  Once I got there, I added a second round into the mag and made sure it would eject and load the rounds properly.  I was able to successfully fire off 7.62x51 149 grain brass rounds and 308 WIN 150 grain wolf ammo without any jams or problems probably shot off around 20 rounds.  I also tried 308 WIN 180 grain and it was having a problem ejecting the round completely out, it would pull it out of the chamber but it would be sitting on top of the magazine and not thrown out.  I ran out of time to diagnose further, but I'm thinking I should increase the gas a bit more probably.

The shells are landing at about 3:30.

Thanks for everyone's help and suggestions!  I greatly appreciate it!

 

 

Edited September 5, 2021 by thossoma@pm.me

[98Z5V]

That's the backwards way to play with an adjustable gas block, but glad it's running.

Always run an adjustable gas block WIDE OPEN, as far as it will go, when testing a build. Everything else is a waste of ammo. Dial it down to what you want, after it runs reliably. 

[jtallen83]

^^^ That right there. You will want to revisit the gas setting after a good break-in period.

[thossoma@pm.me]

Good to know!  This would be my first time with an adjustable gas block. I have questions then...

1. Should I start over wide open and then watch where the shells fly? 

2. Is 3:30 a good spot? Or what position tells me that I have dialed it correctly?

3. How many rounds would be considered a good break in period?

Thanks again.

[jtallen83]

16 minutes ago, thossoma@pm.me said:

Should I start over wide open and then watch where the shells fly? 

Wide open then back down to failure to lock back, back up a notch or two or three depending on your priority, softness vs. reliability, just remember this is tuning to a specific ammo, adjustment may be required with changes. Changes in a guns ejection pattern are a good indicator of weakening springs. I never care where they go to start as long as the gun runs, just try to pay attention to changes...... can't hardly afford to wear out springs these these days though.

[98Z5V]

With a full gun that is broken in, you start wide-open on the adj gas block for one reason.  Test the size of the gas port in the barrel.  Gas block wide open, one round in the mag, test single-round lack back.   One round in the mag SHOULD lock the BCG back, right after you fire that one round. 

If the gun is broken in - if it doesn't lock back after one round in the mag, with that adj gas block wide open - then that tells you that the gas port diameter in your barrel isn't large enough.

Every other process is just a waste of time, ammo, and money. If it doesn't lock back - you address the gas port issues, very first.

[98Z5V]

33 minutes ago, thossoma@pm.me said:

1. Should I start over wide open and then watch where the shells fly? 

 

Don't even worry about ejection pattern, right now.  "Election Pattern" sells buffers, nothing more.

I don't care where the brass goes, as long as it gets OUT of my chamber, then gets OUT of my gun.  Anything else is butter.

Buffer weights tune where your brass lands.  That's the bottom line.  With an adj gas block, you need to make the gun RUN first, with already having a solid recoil system in place before you started, and THEN you play with gas pressure.  Start Adj Gas Blocks wide open.  No other way to tell if the gas port in the barrel is large enough.  No other way.

[98Z5V]

18 minutes ago, 98Z5V said:

 

 With an adj gas block, you need to make the gun RUN first, with already having a solid recoil system in place before you started, and THEN you play with gas pressure.  Start Adj Gas Blocks wide open.  No other way to tell if the gas port in the barrel is large enough.  No other way.

PSA fails on this routinely.  They send PSA PA-10s out the door with AR15 recoil system parts in those guns.  Been documented many. many. many times.  They just don't care.

It's pretty easy to determine if one of the large-frame guns is "overgassed" - the MOST common mis-diagnosis, in all of times...  OR if the gun left the factory UNDER=RECOILED.  

Everyone that tells you that you need an Adjustable Gas Block to even make your standard gun run - is full of bullshiit.  Standard guns should run out of the box.  If the answer is "adjustable gas block" - then your recoil system isn't up to par.  it's far BELOW even what the minimum standard is.

But, cheap manufacturing processes make cheap guns that shoot cheap ammo, for most of the people out there that will never know the difference in the first place - and those cheap guns will work for those cheap rounds that most of the people looking for a cheap gun. And when that cheap gun fucks up - they won't care - or maybe they will, and they'll send it back for that "lifetime warranty."
 

The answer they get back is that the gun is fine, worked during testing, no issues.

I'm not clairvoyant - already seen that a few times here. 

Edited September 5, 2021 by 98Z5V

[thossoma@pm.me]

On 8/27/2021 at 6:51 PM, thossoma@pm.me said:

So the drill bits came today.  I got it drilled out and did some test firing.

The first thing I tested is I put 1 round in my magazine to see if it would lock back the bolt.  I was happy to see that it did lock back and ejected the shell!

So prior to the adjustable gas block I was able to get the bolt to lock back after shooting the last round from the mag because I drilled the gas port out with a #44 drill bit as suggested.  But jamming still occurred pretty badly.  It was also suggested that I dunk the BCG in a bath of oil then wipe it's face, slam it in and start shooting.  I ended up purchasing the Adjustable gas block because of some other recommendations and installed it before test firing yesterday.  I'm assuming that the oil bath is what actually made the gun start working properly and not the new gas block, but I do like the extra flexibility of having that anyway.  I will continue to put rounds through it and make sure the bolt is dripping wet.

Another question I have is about bullet weight as it compares to amount of gas going through the gas tube.  Does a heavier bullet require more or less gas to cycle to bolt back?  Or does it not even matter the weight of the bullet?

The AR-10 world is so different then the AR-15 world.  I built two AR-15's and have shot multiple different bullet weights through them without issue. And when I put the gun together I had no issues firing right out of the gate, different story with the AR-10.  I'm glad that you guys were available to give me guidance and get it working for me.

[Albroswift]

1 hour ago, thossoma@pm.me said:

Does a heavier bullet require more or less gas to cycle to bolt back?  Or does it not even matter the weight of the bullet?

Once I have the gas and recoil tuned, mine shoot 150-180 gr without ever messing with the AGB.  If your system was borderline, bullet weight could make a difference. I would think lighter bullets take slightly more gas, but I could be 180% off on that. 

[shooterrex]

Not all ammo is the same. Different bullets, different powders w/different burn rates.  You might need to open the gas block up a bit more to get the 180's to cycle. Also the new gas block probably isn't sealed w/carbon just yet.

I open it up so it runs anything I put in it. It may recoil a bit more than it could but it eats everything I put in it.

[unforgiven]

I just don't get the need for a adjustable gas block. A lot of fukin around for minimal gain. I was able to shoot suppressed and  unsuppressed with out one. Seems like a waste of ammo and a lot of fiddle fukin. I don't have anything adjustable on any rifles because I don't want to have anything to fall out of adjustment. Just my 2 mags. Why complicate $hit with complicated $hit. I just don't get it. 

[Albroswift]

 

2 hours ago, unforgiven said:

A lot of fukin around for minimal gain.

I think about it differently, instead of trying to hit the correct port size right off, start with one big enough to be known to work, and then back off a little until tune is perfect. on my 12.5 I switched out my recoil system from a SB3, 7-11/16" tube, EA1095 spring, 3-1/2" buffer to a Tailhook Mod 2, 7" tube, Sprinco Orange spring, 2-3/4" buffer, and all it took was a couple of clicks and all sweet again. Never have a problem with AGB going out of adjustment, and if you initally adjust them from wide open back as @98Z5V recommends you don't burn very many rounds at all. For me it works.

[unforgiven]

I can see that on a compact rifle setup but what about 14.5 and up?

[jtallen83]

I have a pile of adjustable gas blocks, wanted that adjustability for suppressor use. Number one thing overall I have noticed is I rarely adjust anything, bunch of different specific reasons for that but facts is facts. I actually removed one from a 300 BO build, it has become part of the secured "storage device" for a suppressor, no need to put anything in there that could grab carbon fouling, reliability requirement called for uncomplicating the gun a bit.