New Member, and troubles with my Homebuilt AR

[jtallen83]

11 hours ago, Elmer75 said:

Is it possible that the chamber is rough and grabbing the casing? If so, is there anything to do about it?

I've had luck using jewelers rouge on a chamber mop, spin it up with a drill, little bits at a time till I see the shine. 

[jtallen83]

11 hours ago, Elmer75 said:

The marks on the casing make me think the chamber is not very smooth.

Rough chamber marks are usually circular, rings or shadows around the brass.

[Elmer75]

1 hour ago, jtallen83 said:

Rough chamber marks are usually circular, rings or shadows around the brass.

So not like the marks shown in the picture....

[jtallen83]

32 minutes ago, Elmer75 said:

So not like the marks shown in the picture....

I don't see the rings in the picture but they don't always show what you see in person. 

[Elmer75]

These light marks show up after the round is chambered.  It seems like something in the chamber is creating them.  They show up on rounds that are fired or not.  If I chamber the same round twice, I get more marks.  This is why I'm wondering if there is something in the chamber that is grabbing the round.

[MJV83]

I’m definitely short on knowledge compared to everyone else here, but have you taken apart the BCG? First time I took mine apart, there was 2 o-rings installed around the spring. I’ve also read of numerous others finding double o-rings installed. Not exactly sure why some manufacturers do that?? Maybe someone else here knows. And possible could be a cause of the extraction issue?

[98Z5V]

2 hours ago, MJV83 said:

I’ve also read of numerous others finding double o-rings installed. Not exactly sure why some manufacturers do that??

Increases pressure on the extractor, so it doesn't drop the casing mid-way out of the chamber.

[MJV83]

On 5/30/2022 at 10:47 PM, 98Z5V said:

Increases pressure on the extractor, so it doesn't drop the casing mid-way out of the chamber.

So it’s supposed to be a double O-Ring in there? I have a Ballistic Advantage BCG that came paired with the 20” premium series BA barrel. I took the extra one out thinking it wasn’t supposed to be there, but since my rifle hasn’t cycle properly yet, I don’t know if it’s doing anything good or bad? Should I put the second one back in? I’m going to the range tomorrow and hopefully the rifle will cycle properly after the “tweaks” I made to it…thanks again for the help with that!! 

Im thinking I might as well put it back in, as it’s something I can easily remove at the range if the need arises.

 Do you keep both O-Rings installed on your BCG?

[mrmackc]

No extraction, maybe a rough chamber, I would use a borescope to take pics of the chamber, close the adjustable gas doditty about 1/2 way. do that right away, and like the man said lube up everything back of the chamber with Mobil one 10W40 motor oil dripping wet.  I'm not sure that Frittz or JB bore paste will only clear the bad place in the chamber.

I would probably contact the barrel builder for another barrel, what with the way too small gas port and the obviously flawed chamber. It just was not done right.

[98Z5V]

22 hours ago, MJV83 said:

Do you keep both O-Rings installed on your BCG?

I do, if they came with them.  Sometiimes 2, sometimes 1.  I leave in what it came with, unless I'm having specific extraction problems that I can tie directly to that. 

[Elmer75]

Hey All,

I finally have some follow-up on the failure to extract, failure to feed, and lock-back issues with my 308.

I contacted the barrel mfg in June to see if they had any thoughts on the issues.  After some back and forth they suggested that it could be a defective BCG that they supplied with the barrel.  I returned the old BCG and they sent out a new one, and I finally got a chance to test the rifle yesterday.

The rifle operated flawlessly with no changes other than a new BCG.

The first test was for positive extraction.  3 rounds in the magazine and all 3 rounds extracted and ejected fine.  All rounds fed with no issues.

The next test was for positive lock-back, loading only one round in the magazine.  I started out with the gas port screw at 2-1/2 turns open, and the bolt locked on the first try. I turned the screw down 1/4 turn each shot, and got positive lock-back until I had the screw at 1 turn open. Back at 1-1/4 turns open I had consistent lock-back with 15 rounds of different ammo.  I set the port screw at 1-1/2 turns open and locked it in place.

I'm very please with how the rifle operates.  Now I need to practice my shooting, as the rifle currently shoots better than I do.  I'll be posting some questions in the near future, starting with what type of scope I need for the rifle.

And thanks for all the help getting the rifle sorted.

 

[98Z5V]

3 hours ago, Elmer75 said:

Hey All,

I finally have some follow-up on the failure to extract, failure to feed, and lock-back issues with my 308.

I contacted the barrel mfg in June to see if they had any thoughts on the issues.  After some back and forth they suggested that it could be a defective BCG that they supplied with the barrel.  I returned the old BCG and they sent out a new one, and I finally got a chance to test the rifle yesterday.

The rifle operated flawlessly with no changes other than a new BCG.

The first test was for positive extraction.  3 rounds in the magazine and all 3 rounds extracted and ejected fine.  All rounds fed with no issues.

The next test was for positive lock-back, loading only one round in the magazine.  I started out with the gas port screw at 2-1/2 turns open, and the bolt locked on the first try. I turned the screw down 1/4 turn each shot, and got positive lock-back until I had the screw at 1 turn open. Back at 1-1/4 turns open I had consistent lock-back with 15 rounds of different ammo.  I set the port screw at 1-1/2 turns open and locked it in place.

I'm very please with how the rifle operates.  Now I need to practice my shooting, as the rifle currently shoots better than I do.  I'll be posting some questions in the near future, starting with what type of scope I need for the rifle.

And thanks for all the help getting the rifle sorted.

 

This is good news, man - very well done. 

Did the company ever state what the issue was with the original BCG?

[shooterrex]

Great to hear it's running now.

[Elmer75]

8 hours ago, 98Z5V said:

This is good news, man - very well done. 

Did the company ever state what the issue was with the original BCG?

Nope, they only said they had a bad batch come through and that it might be one from that batch.  I may follow up and see if I can pry a little more info out of them.