AR10 6.5 creedmoor, is copper blob on gas port common?

[rockwind1]

UPDATE 12/21/23
criterion looked at my pics and are sending a new barrel. i keep trying to get the blob out and that thing is being tenacious,, i recently poured boretech eliminator thru the muzzle so i flowed over copper and down gas hole and let it sit for a couple days, got some blue stuff out but blob is still there.

new criterion barrel, 16" rifle length gas tube, about 50 rds thru it. i had just cleaned and rechecked with borescope and found this blob on the exit side. is this somewhat normal?
i will remove with some boretech or similiar copper remover but it seems to shoot ok.
just wondering. these are 2 seperate pics

 

[supercorndogs]

It tends to be problematic to have the gas port crossing a land like that. They tend to gather copper towards the muzzle end of the port like you are seeing. I would send them a picture and complain about it personally.

 

[Namekagon]

Hell if it shoots who cares.

This could be fairly common. It’s only recently that society has degraded to the point where men go around every day with fancy mirrors to stare at their own gasholes

 

[supercorndogs]

Could be very good for the consumer to be able to look at gas holes and diagnose problems like this one. Accuracy drops off after unusually low amount rounds without cleaning. Its not super hard to make a jig to make sure gas ports are in the grove not the land. Or replace a barrel when the customer calls you on not locating your gas ports and hope the next one is halfway in the groove.

 

[Stavey]

While some erosion is normal . I can’t say I’ve seen copper like that. Almost looks like a piece of copper/jacket. What supercorndog stated is true. When I ordered my last 6.5 barrel from Krieger. I asked about a 5r. I was told they do not do 5R barrels for AR10s. Said that with the 5r it’s too difficult to center the gas port on a land.

 

[Rocketvapor]

That looks like port stripping jacket material from Hornady bullets.
Port should smooth out with shooting but expect fliers and bullet blow ups as the copper blob will damage bullets.
It may also act as a slight bore obstruction as the bullet shudders across the blob.
Look for primer catering.

 

[rockwind1]

I was having some over pressure problems with a particular factory ammo and after checking some other things, i decided to bore scope it.

 

[spooledup]

It will only get worse in that location. I had the same issue with a Proof barrel and accuracy went south quickly. I pulled it and sent in back to Proof. Once they inspected it a replacement was offered.

I’d call and get the ball rolling. It won’t get better in that location, only worse.

 

[loclass]

If it shoots, don't sweat it. If it's giving you problems, call the manufacturer.
I have a Compass Lake AR15 barrel in 6 ARC that has the shittiest chamfer ever around the gas port and the wear is more than I've seen on any other barrel I own, but after 1500+ rounds the accuracy hasn't degraded. I don't like the way it looks, but the results downrange are hard to argue with.

 

[rockwind1]

If it shoots, don't sweat it. If it's giving you problems, call the manufacturer.
I have a Compass Lake AR15 barrel in 6 ARC that has the shittiest chamfer ever around the gas port and the wear is more than I've seen on any other barrel I own, but after 1500+ rounds the accuracy hasn't degraded. I don't like the way it looks, but the results downrange are hard to argue with.

i should elaborate, when i say it shoots, it's nothing to write home about, and the ES has increased to about 110 vs first box of same ammo which the ES was around 40 ish.

and this has only been about 50 rds. i will see what they say. it's too bad there isn't a tool on a shank thta has a slight angle grinder on it that you can put thru gas hole and smooth it out a bit.

 

[msgriff]

Turning a 6 groove into an unbalanced 5 groove.

 

[STI_1911_Guy]

It will only get worse in that location. I had the same issue with a Proof barrel and accuracy went south quickly. I pulled it and sent in back to Proof. Once they inspected it a replacement was offered.

I’d call and get the ball rolling. It won’t get better in that location, only worse.

I agree. I had a couple like that and they never shot what they should have. Wasnt super awful but probably 1.5-1.75moa when the barrel before shot sub 1moa consistent.

 

[lennyo3034]

I’ve had ports that look way worse than anything in this thread and the barrel still shot amazingly.

 

[rockwind1]

I’ve had ports that look way worse than anything in this thread and the barrel still shot amazingly.

i will play around with it some more but it is amazing the wide range of observations on the subject. i still can't imagine the bullet doing well with some of the jacket missing but i guess that is why i posted on here,, I just really don't know. i do know the ES on the hornady sure increased after a box

 

[msgriff]

I doubt that all of the jacket is being stripped off on the "blob". I would imagine that the "blob" is acting more like a false land and imprinting on the bullet. That imprinting would affect the balance of the bullet, as it's no longer symmetrical. It would be interesting to see a recovered bullet from a trap, but that would be difficult for rifle bullets outside of equipment at a testing lab.
That gas port location would make using this tool less than ideal, but this type of deburring/chamfer bit might help the "blob" from reappearing. Or just let Criterion deal with it.

 

[232593]

That looks like port stripping jacket material from Hornady bullets.
Port should smooth out with shooting but expect fliers and bullet blow ups as the copper blob will damage bullets.
It may also act as a slight bore obstruction as the bullet shudders across the blob.
Look for primer catering.

Do you think something similar on the gas port of a 22 CM could cause bullets to come apart?

How many rounds does it normally take to smooth it out?

 

[ZA206]

Definitely an issue! They should replace that barrel. Having the gas port cut entirely through a land is a big no no! WOA recently replaced one of my 223 Wylde barrels because of it (wouldn't group smaller than 1.5" no matter the load).

 

[rockwind1]

Definitely an issue! They should replace that barrel. Having the gas port cut entirely through a land is a big no no! WOA recently replaced one of my 223 Wylde barrels because of it (wouldn't group smaller than 1.5" no matter the load).

yes, i am going to update post,, criterion is being very stand up-ish and they are sending new barrel with return label.

it must be tough to put gas port right thru a "valley" part of the rifling right? i mean, an ar barrel can't be rotated and the gas port has to be pretty exact distance from the breech for the gas tube to protrude properly,, i mean, i don't make barrels so i don't know how they would get around that.

 

[rockwind1]

That looks like port stripping jacket material from Hornady bullets.
Port should smooth out with shooting but expect fliers and bullet blow ups as the copper blob will damage bullets.
It may also act as a slight bore obstruction as the bullet shudders across the blob.
Look for primer catering.

i just noticed you mentioned primer cratering,, there is a slight amount but i am getting some other pressure signs, blown primer, ejector marks, flat primer,, which i have been addressing and that is why i wound up borescoping it cause i wanted to see if there was anything unusual. But no idea if copper blob is the cause. Doesn’t seem likely. Was experimenting with buffer weight until got squirrelled with barrel blob.