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Old October 6, 2021, 05:54 PM   #26
Shadow9mm
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Originally Posted by BornFighting88 View Post
Could it also be his recoil assembly?? I get that it is over gassed, that makes complete sense to me. It is opening too soon, chamber pressure too high and brass hasn’t relaxed yet. This would allow the extractor to rip off that thin small rim. I buy that.

There are some that believe the standard Mil-Spec recoil buffer assembly is for rifle length gas systems. I don’t necessarily follow that path. Gun designers (usually) aren’t dummies, and they make working products. But in this case, I would pose that question, just to say I did. Could a more stout or heavier recoil buffer help?? If the system has to move more weight/mass before it can start its cycle, could it be opined that a heavier buffer could aid in (not completely solve) this situation??
If it's ripping the rim off, a heavier buffer would improve things but I would be surprised if it fixed the problem. That's more of a,, fine tune, vs, fix a problem kind of thing in my experience
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Old October 7, 2021, 04:49 PM   #27
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OK, anybody ready for a gunsmith's input? I know you guys love your personal favorite theories of why, but basic troubleshooting will figure out what the cause of the malfunction is.

Was this barrel designed to fire subsonic ammo suppressed? If so, the gas port is likely too large.

Do the feed ramps line up properly at the breech? I see a lot of ARs that need the feed ramps cut properly. If not cut properly, they buckle the case neck while feeding and the rifle will jam.

Is the barrel chrome-lined or melonited? If so, you will not likely polish out any chamber imperfections.

Try removing the gas tube and firing, then try to extract the fired case. That will narrow it down quickly if it is overgassed.

Try feeding a round from the mag and extracting it using the charging handle. That will tell you if it's a feeding issue.

Lots of things to check before ever getting near checking headspace and polishing the chamber.
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Old October 7, 2021, 06:21 PM   #28
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Was this barrel designed to fire subsonic ammo suppressed? If so, the gas port is likely too large.
No, Bushmaster offered this barrel in their Quick Response Carbine, was lightweight barrel, 16 inch, sold with A2 flash hider on it, wasn't designed to fire subsonic suppressed.

Do the feed ramps line up properly at the breech?
Yes, they line up nicely.

Is the barrel chrome-lined or melonited?
Damn it, I didn't think about that yet. Yes, it's black nitride/melonited
When I knocked the brass case out of the chamber, it came out scratched and there was brass specks caught in the rough area in the chamber. I called a local gunsmith who's supposed to take a look at it Saturday to see if the chamber can be cleaned up and saved.
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Old October 7, 2021, 07:09 PM   #29
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If you saw these things when you knocked the round out,why do you wait till now to tell us?
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Old October 7, 2021, 07:52 PM   #30
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I don't think it's especially unusual for brass to be somewhat abused in the process of cycling, firing and ejection, especially with brand-new sharp edges of components not having worn a bit. Might need some stoning of things like lugs.
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Old October 7, 2021, 08:31 PM   #31
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If you saw these things when you knocked the round out,why do you wait till now to tell us?
Sorry about that, just got back to taking things apart and looking at them a little more carefully. Once I got the case knocked out and looked in the chamber with the bore light, there's a rough area in the chamber just before what I'd call the shoulder of the chamber, and is a full circle of rough machining. I didn't notice it at the time of assembly with a clean chamber but when I got the brass case out, the remaining brass specks caught in the rough section stood out boldly in the light.
But, Scorch mentioned melonite and I'd forgotten it's been nitrided and now wondering if the chamber can be cleaned up?
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Old October 8, 2021, 10:22 AM   #32
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A possibility is the chips got packed up in the reamer and galled in the area of the roughness.
Whatever QC process Bushmaster used,likely some barrels were quarantined for disposition. It might be chopping the sights off was a way of marking them so they would not escape.

With the plant shut down,someone bid on the leftovers or got the job of cleaning up the building.
A scrounger put the barrels in question up for sale to make a few bucks.

You come along,see a "bargain" and buy it.

Now that barrel is a problem,and all the solutions are throwing good money after bad.
You do what you want,

I just do not understand putting the investment of the rest of the rifle into a "bargain" barrel.

I darn sure would not put the money into having a pro try to put lipstick on a pig. Call it a lesson learned.

https://www.aeroprecisionusa.com/ar15/barrels

Last edited by HiBC; October 8, 2021 at 10:29 AM.
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Old October 8, 2021, 12:14 PM   #33
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I bet you're fine and are not on the cusp of AR repairs Armageddon, don't freak out and do anything radical. First (simple) thing first: Charge the bolt carrier back--take a clean new cartridge (measure it and take pictures of it) and drop the bolt carrier on it. Then try to extract it manually (without firing). Does it come out or not? Does it show signs of damage or not? Even a caveman could do it. (as I previously mentioned, do this with the weapon pointed at a target with backstop that you don't mind being destroyed).
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Old October 9, 2021, 12:14 AM   #34
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I wasn't looking for a bargain barrel, I was looking for lightweight barrel, carbine length gas, nitrided, and preferably with a 1:8 twist. This Bushmaster checked all the boxes and I'm disappointed it didn't work. I can't find another barrel with same specs.
So, I'll have to go with Ballistic Advantage Hanson barrel or Faxom Gunner, but both are mid length, I'd prefer carbine length, and I still need to be able to mount a handguard cap behind the gas block, easier said than done as most low- pro gas blocks rest against the gas journal shoulder. Faxom already confirmed their gas block rests against the shoulder of their barrel with no room for a handguard cap. A short free-float handguard would simply things, but it's not the build I have in mind.
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Old October 9, 2021, 09:38 AM   #35
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Is the gas block pinned to the barrel and then nitrided (sorta like the fixed post sight)? Sounds like it's set up for a conventional delta ring/glacier guard set-up. This can be tough to get off and then you still have the cuts in the barrel.
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Old October 9, 2021, 03:28 PM   #36
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Admittedly,its far too easy for me to spend another man's money.

Food for thought:

https://danieldefense.com/16-5-56mm-...w-profile.html

And:

https://www.midwestindustriesinc.com...-ulw12.625.htm

Thats a barrel and a light free float forend. They are good stuff.

Do use your phone to verify compatability..

It is a chrome lined hammer forged barrel. My 18 in S2W contour shoots just over an inch at 100 yds.

The Midwest Free Float forend is nice and will give better accuracy than the GI setup.
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Old October 10, 2021, 07:10 PM   #37
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UPDATE:
Just got an email from the guy who sold me the barrels. who just heard from his distributor. who reported that the barrels weren't cleaned properly after the nitriding and that they've had to use a .223 bead hone in the chambers to get some of them to work correctly.
Nope nope nope...not me, not gonna hone the chambers, both barrels are going back for a refund.
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Old October 12, 2021, 10:24 AM   #38
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When I read you had to knock the fired case out, I knew this wasn't going to be an over-energetic gas system. A fired case should fall out or at most need a light tap after the pressure is gone.

Bushmaster is back in business in Carson City, NV, as of August this year. I suggest you send it to them and let them fix the problem. Honing nitriding will thin it. Best to get one that was done correctly in the first place.
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Old October 13, 2021, 09:49 AM   #39
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When nitrided it's not uncommon for some residual scaling to form. It can have no impact, minor scarring of case, or in minimal cases it can cause a malfunction. As previously stated, a smoothing as suggested usually corrects the anomaly.
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Old October 13, 2021, 05:35 PM   #40
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I second Unclenick on this. Let the factory deal with it. Their product, theirs to fix.
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Old October 15, 2021, 01:25 PM   #41
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Bushmaster is back in business in Carson City, NV, as of August this year. I suggest you send it to them and let them fix the problem. Honing nitriding will thin it. Best to get one that was done correctly in the first place.
I've left them a couple of emails and a couple of phone calls, can't get a response from Bushmaster at all. So, unfortunately looks like I'm going to have to send the barrels back to the seller and go with a different barrel like a B.A. pencil barrel or a Faxom Gunner.
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Old October 15, 2021, 04:05 PM   #42
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How much did these barrels cost you?
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Old October 15, 2021, 05:54 PM   #43
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How much did these barrels cost you?
Fortunately they were only $100 each, plus $20 shipping, and seller is offering full refund once I ship them back.
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Old October 15, 2021, 06:13 PM   #44
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Probably better off spending the whole kitty on a name brand quality barrel.
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Old October 17, 2021, 07:41 AM   #45
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Guns are something I do my best NOT to cheap out on. Even if it means waiting and saving for the proper components. I did something similar, wasn’t a barrel, but an important part for the fire control. Was Uber affordable, and picked it up and was never happy with it. Ate the cost of that one, and the cost of the better product. Lesson learned.
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