"Fissures" inside my AR barrel - normal?

[gunsrfun1]

Hopefully I will describe this issue clearly enough to get some answers. I received a Del-Ton carbine-length upper last week and started checking it out today. Overall build quality seems very good, and it fits my RRA lower nice and snug. (More snug in fact than my Stag upper does.)

However, after swabbing out the barrel, I noticed that there seem to be some horizontal "striations" or "microcracks" or "fissures" running horizontally down the barrel. They do not run the entire length of the barrel and are random. And of course they are not so rough as to be able to feel them if you run a Q-tip down the bore. Best way I can describe them is looking like minute cracks or maybe machine marks.

I am no expert on ARs. I do have two other uppers, a RRA and a Stag, and both of their barrels are pristine. (The Stag is chrome-lined, the RRA isn't). The Del-Ton is unlined chrome moly vandadium, whatever that means.
So it's obviously not a match-grade barrel, but I wasn't expecting one. I'll be using this as a "fun/maybe tactical" setup and plan to apply a magnfication scope for shooting at 100 yards and beyond. But I don't plan to play sniper at 1,000 yards.

My question is whether this constitutes a "defect" that I should return it for, or whether it's no big deal and I should shoot it to see if accuracy is affected.
My preference is to shoot it first, because I do know from some other guns I've had that condition of the barrel doesn't always directly relate to accuracy. But if it's obviously a defect, I'd want to return it.

What do you think?

 

[joeschmoe]

Pics? Contact manufacturer to ask them what they think. They have probably experienced this issue before. Could be something, could be nothing. If they fear any liability, they will ask you to return it for repair. If they think it's just a cosmetic thing, then forget it. Doesn't sound good, but maybe just minor roughness that will go away after a few rounds. Better safe than sorry with high velocity.

 

[ApacheCoTodd]

Sure doesn't sound good.

I'd be curious to know if they fray a high quality patch (wet and dry) when puled through from either end.

What state do you live in? AZ - I've got an excellent bore scope for a look-see.

 

[gunsrfun1]

No it did not fray a patch. But I am going to contact Delton and ask them. I don't like to be overly picky, but for $400 I expect a barrel in good shape. Thanks.

 

[colorado_handgunner]

FIRST: DO NOT SHOOT OUT OF THIS BARREL AS SERIOUS INJURY OR DEATH COULD RESULT FROM THE BARREL SHATTERING.

Now to explain.

Sounds like micro fractures from the manufacturing process. Usually you can only see that kind of defect after magnafluxing the parts, unless the fractures are severe, then you can see it with the naked eye. I imagine they are only on the inside since the interior of the barrel was probably more heavily machined after heat treating. Pictures would certainly help.

However, if it is micro fractures, the problem is that the fractures indicate there are residual stresses in the metal of the barrel, usually a result of faulty heat treating.

Once you apply the pressure of a fired round, the stresses may "snap" resulting in a catastrophic failure of the barrel along the stress lines.

For background. This is from my past experience in bearing manufacturing and heat treatment.

AGAIN: DO NOT SHOOT OUT OF THIS BARREL AS SERIOUS INJURY OR DEATH COULD RESULT FROM THE BARREL SHATTERING ALONG THE STRESS LINES.

Send it back for inspection.

That is my opinion anyway.

 

[gunsrfun1]

Thanks. Will contact Del-Ton and reference your input.

 

[colorado_handgunner]

Very good. Hopefully it is not micro fractures and all is well, but not worth the risk, in my opinion. Let us know how it goes.

 

[taliv]

how did you see them? with a bore scope? or are they on the outside?

 

[gunsrfun1]

With a bore light, and a head magnifier.

 

[MistWolf]

You'll need to have the barrel borescoped to determine of there is a real problem

 

[gunsrfun1]

I contacted Delton and they asked for some pictures. So here are some of what I sent them. Hard to really see much without being right on top of it, but best I could do.

 

[mtrmn]

Sorry but all I can see is normal rifling.......

 

[gunsrfun1]

I returned the upper to Del-Ton; they paid shipping. They contacted me today and are sending me a replacement upper. Guess they found something after all.

 

[meanmrmustard]

I returned the upper to Del-Ton; they paid shipping. They contacted me today and are sending me a replacement upper. Guess they found something after all.

I saw it.

Good eyes, by the way.

 

[Trent]

Hey good news! Nice to hear Del Ton backs up what they sell.

I've been kicking around getting a good bore scope for years, but every time I get serious about it something shiny catches my eye and I spend the money I'd earmarked.

 

[colorado_handgunner]

Glad they made it right, and more importantly, no one was hurt firing a damaged barrel.

 

[Onward Allusion]

^^^^
This is why I come back here... Very knowledgeable bunch of people from all walks of life, including folks with engineering backgrounds. Probably saved the OP from some pain & suffering or worst.

 

[gunsrfun1]

Conclusion

I ran across this post and thought I would follow up to close it out. I did eventually get a new upper from Del-Ton. Bottom line, without going into a lot of detail, is that the upper was better than the last one, but still had some issues. Del-Ton resolved them after I badgered them a bit. But I won't be buying anything more from them. I eventually sold the upper, because I decided I wanted an upper without a fixed from sight.

 

[itsa pain]

del ton is upper tier AR parts. it goes to show you that you do not always get what you pay for

 

[Quentin]

Thanks for the update and sorry you had problems with the replacement upper. A crying shame, DTI should have made absolutely sure the replacement upper was 100% after selling you the first with a serious barrel defect.

What were the problems with the second upper, other than you didn't want a fixed front sight? Like you, I'm not a fan of DTI after helping a buddy with his. The main problem with his was an absolutely horrible fire control group, the worst I've ever seen. A replacement FCG brought the trigger up to par with average milspec feel. I tried to like DTI since they're from my birth state but there's no way I'd buy from them when there are so many better choices at the same price point.

 

[243winxb]

That was a sad looking barrel. Good test for Tubb's FinalFinish Bore Conditioning System

 

[Mobuck]

For all I know all my AR barrels might have such scratches but I don't look for them so they don't bother me. I clean them and shoot them. If they shoot satisfactorily, I keep them. DelTons are some of the most accurate standard grade AR barrels I've encountered.

 

[adelbridge]

I eventually sold the upper, because I decided I wanted an upper without a fixed from sight.

Hope you didnt loose too much. Takes all of about 15 minutes to change a sight.