Thoughts on this AR-15 Barrel, to buy or not to buy?


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dust_101
July 10, 2007, 03:29 PM
Well folks I am now starting down the long dark road of building up my very first AR series rifle.

I usually check local places first for parts, and came across this:

Numrich Arms Barrels (http://www.e-gunparts.com/DisplayAd.asp?chrProductSKU=982930&chrSuperSKU=&MC=YJ)

I called over and they are out of stock on most of these, but the one I need for NY State is the first on the list "MT6530 16" 5.56 NATO Match Target Lightweight Sporter - 1/7 Twist - Post Ban Non-Threaded - Non-Chrome Lined" and it is in stock.

Think that is a good deal on the barrel? I'd be paying tax but no shipping.

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cheygriz
July 10, 2007, 03:50 PM
I wouldn't even look at one that wasn't chrome lined with a MilSpec 5.56X45 Chamber.

romma
July 10, 2007, 04:13 PM
I wouldn't even look at one that wasn't chrome lined with a MilSpec 5.56X45 Chamber.


Ditto that cheygriz

SnakeEater
July 10, 2007, 05:10 PM
I wouldn't even look at one that wasn't chrome lined with a MilSpec 5.56X45 Chamber.
Good advice, but stainless barrels with Wylde chambers are a wee bit better IMO.

glockman19
July 10, 2007, 05:13 PM
I wouldn't even look at one that wasn't chrome lined with a MilSpec 5.56X45 Chamber.
+2

scubie02
July 10, 2007, 05:22 PM
I'd probably go for chrome lined on a 16" barrel I suppose, but it's probably not that big of a deal.

On the other hand, I have a complete upper you could get a deal on...=)

blackhawk2000
July 10, 2007, 05:28 PM
Good advice, but stainless barrels with Wylde chambers are a wee bit better IMO.

Good for what? Target shooting?

As they say go chrome, or go home.

RockyMtnTactical
July 10, 2007, 05:29 PM
I wouldn't even look at one that wasn't chrome lined with a MilSpec 5.56X45 Chamber.

Agreed.

SnakeEater
July 10, 2007, 05:41 PM
Good for what? Target shooting?

As they say go chrome, or go home
Yes, target shooting. Personally speaking targets are the only things I shoot at. Yes CL will last longer, but barrels are easily replaced. After the SS barrel has about 10000rds through it accuracy will fall off to roughly what a new CL barrel shoots. Wanna hear another catchy phrase?

Only accurate rifles are interesting. Col. Townsend Whelen:evil:

dust_101
July 10, 2007, 07:37 PM
scubie02 - that is one nice upper you have on the ads, but for my build I'm going for a more military-style lighter rifle for use on 3-gun and not just varmint/target. good price on yours though... tempting....

As for the CL ones with a MilSpec 5.56X45 Chamber... can someone link up one on here so I can see what type of price these go for, and if there are any that are not threaded?

mc223
July 10, 2007, 07:44 PM
http://www.bushmaster.com/shopping/barrel-assemblies/pbbl-20a.asp

Bartholomew Roberts
July 10, 2007, 08:52 PM
Well, considering that a non-chrome lined Colt barrel did 10,000 rounds in a single weekend, I think you would be OK with non-chrome lined if the price was right. IIRC, throat erosion started to affect accuracy around 9,800 though.

I have both a 4150, chrome-lined 5.56 1/7 barrel (CMMG) and a stainless steel Wylde-chamber 1/8 barrel. Right now I prefer the stainless; but we'll have to see how it does longevity wise. My last chrome lined barrel (16" 1/9 Bushmaster HBAR) started having long range accuracy issues around 9k rounds, so I am not all that sure that chrome-lining provides superior longevity.

browningguy
July 10, 2007, 09:20 PM
I think it's a decent enough barrel for the price, chrome lined doesn't matter to me at all. I don't shoot corrosive ammo, rarely drag my rifles through the mud, and keep them reasonably clean. The only thing you can do with a chrome lined, mil-spec .223 chamber is impress the girls:), won't do a thing for accuracy.

Actually I'd probably go out of my way to buy a non-chromed barrel with the Wylde chamber as someone else mentioned.

blackhawk2000
July 10, 2007, 09:26 PM
Only accurate rifles are interesting. Col. Townsend Whelen:evil:

LOL


Well based on the light barrel profile, I figured he wasn't going for a target rifle.;)

SnakeEater
July 10, 2007, 09:30 PM
When Bart Roberts speaks it's usually wise to listen.

scubie02
July 10, 2007, 09:34 PM
i wouldn't be concerned with rust or something as far as chrome lined vs non cl--i've never had any of my regular ol barrels rust, with basic maintenance that shouldn't be a huge issue for me. The chrome lined ones in theory heat up a bit slower though, I thought, and take the heat a bit better, which could be an issue with rapid fire.

As far as varminter vs military style--you say that now, but just getting one AR is like just getting one 1911...;P

blackhawk2000
July 10, 2007, 09:57 PM
The main benefit to chrome lining IMO is that it helps with case extraction. Dirty hot AR's need all the help they can get with extraction. Bench resters, and target shooters, don't really have those issues. Neither does the casual user.

trueblue1776
July 10, 2007, 10:04 PM
I am a pretty normal guy, I shoot, at the most, 1000 rounds through my AR-15 annually and I'm not a competition shooter. I have never been hot dropped into Liberia and I could care less about chrome lining. Buy what you want if you can afford it.

Bartholomew Roberts
July 10, 2007, 10:36 PM
The main benefit to chrome lining IMO is that it helps with case extraction.

I think there is some value to that. I know that my stainless barrels sometimes seem "stickier" and cases will be dirtier when ejected. On the other hand I've dumped three mags back to back on full-auto and not had a problem as well as doing some classes where we got the rifles good and hot and the stainless Wylde barrels have run fine as long as the ammo was good.

DnPRK
July 11, 2007, 12:07 AM
16" gas systems can be a pain to get running right. I'd recommend a CMT enhanced bolt carrier that delays unlocking for 16" over-gassed systems, a free float tube of some sort (for accuracy), and a clamp-on gas block (to make installation of the FFT easy).

Building your own firearm gives great satisfaction. I've done many over the years and wouldn't dream of purchasing another preassembled AR.

RockyMtnTactical
July 11, 2007, 12:38 AM
There is no reason not to chrome line your chrome moly barrel if your number one concern is reliability. Some manufacturers charge $30 or so for chrome lining. Other manufacturers chrome line their barrels standard.

The 5.56/.223Rem cases are not tapered all that much so the case makes contact with the chamber for much of the feeding and extracting. That is why it is so imperative that your chamber stays clear of corrosion, rust, and pitting. This was a lesson that was quickly learned by the military when it rushed the M-16 into service in Vietnam.

William Davis, Former Chief, Small Arms Branch recalled that, “The principle problem was a failure to chrome plate the chamber. That was the cause of the serious malfunctions that caused the controversy in Vietnam.”

Chrome will also make the chamber more “slick” than steel, which will enhance feeding and extracting.

Chrome lining increases the life of your barrel. It will ease cleaning and maintenance as well.

The one downside to chrome is an ever so slight decrease in accuracy. This difference in accuracy is practically unnoticeable and will not be missed in a defensive weapon.

Don't Tread On Me
July 11, 2007, 07:21 AM
EDIT:

Oops...I just realized that you are from New York (I suggested the 1/9 that has the threaded muzzle and chrome lining)


Sorry.

dust_101
July 11, 2007, 03:13 PM
DnPRK - so if I gather what you're saying, there are more issues with a 16" barrel and getting the gas system to function correctly with the bolt carrier?

As for the CL vs Non-CL and the reasons behind each, for my uses this rifle will be going to the range once a month, it won't be shooting surplus ammo, and as I'm in NY there will be only semi-auto fire, probably with the 10 round mags unless I can find some pre-ban made larger capacity ones.

Myself I'm leaning more towards the barrel at Numrich Arms, I called and they are out of any CL ones that are not threaded... and in NY threaded is not good :(

mljdeckard
July 11, 2007, 03:28 PM
I always say chrome lined, BUT, IF you don't, make sure you aren't mismatching ammo. (.223 in a 5.56 chamber, for example.) I think this is where most of the problems in extraction come from.

trueblue1776
July 11, 2007, 04:32 PM
.223 in a 5.56 chamber, for example.

Isn't it the other way around?

Also, My 16" bushmaster upper has no problems, the "16in barrel is not as good" is irrelevant. You get more pressure from the longer gas tube, but if the shorter one works than who cares?

dust_101
July 11, 2007, 08:11 PM
Quote:
.223 in a 5.56 chamber, for example.

Isn't it the other way around?

Ok stop it, now this is getting confusing... especially since I found out today the barrel at Numrich Arms that I want is stamped "C MP 5.56 NATO 1/7" and also marked "7/00" for a production run of July 2000 from Colt Defense.

This is how I understand it:

TECHNICAL NOTE 45: 5.56 NATO vs SAAMI .223 REMINGTON CHAMBERS (http://www.armalite.com/library/techNotes/tnote45.htm)

blackhawk2000
July 11, 2007, 09:33 PM
You can shoot .223 in a 5.56 gun, but not the other way around. Well you could, but it's not a great idea.

The AR was designed around a 20" barrel. The gas tube on a 20" is the "proper" length. The shorter barrels also have shorter gas tubes (generally speaking). Shorter gas tubes, like carbine length, and the newer midlength gas systems are harder on the extraction process. A 16" barrel with the midlength gas system, is what I would go with. That being said, I have had no problems with my carbine length gas system, other than 2-3 FTE's with Wolf on a dry, hot gun.

DnPRK
July 11, 2007, 09:34 PM
DnPRK - so if I gather what you're saying, there are more issues with a 16" barrel and getting the gas system to function correctly with the bolt carrier?
In a nutshell, yes, 16" barrels can be harder to get running correctly. This is because propellant gas is tapped off closer to the chamber where pressure is higher. Its called "over gassing" which causes the bolt to unlock and attempt to extract the case before the chamber pressure has decayed. Symptoms of over gas is case rims distorted/ripped by the extractor, extractor skipping over the rim (leaving the empty case in the chamber - the symptom seen in Vietnam) or broken extractor hooks. Trying to resolve such problems is a terrible experience for a 1st time builder.

To get a 16" gun to run correctly, all of the following have to be perfect:
1) the propellant has the correct burning rate
2) gas port is the correct size
3) mass of the bolt/carrier buffer is balanced to prevent premature unlocking
4) buffer spring is the correct weight
If any of those 4 are off, you can have a failure to extract and/or failure to feed.

Some folks crutch their 16" builds by adding extra strength extractor springs and o-rings around the extractor (in an attempt to prevent extractor skip over the rim). Others use gas blocks or gas tubes with adjustment screws that allow them to shut off part of the gas flow to the bolt carrier. The LMT enhanced carrier has a different cam pin cut that delays unlocking for a fraction of a second.

None of the above is an issue with a 20" or 24" barrel. The extra 4" of barrel allows the chamber pressure to decay to a level where extraction is easy and not as violent. My recommendation would be start with a 20" build and get it running right. After gaining some experience, you can experiment with a 16" build.

trueblue1776
July 11, 2007, 09:39 PM
Myself and most of the guys I know have AR-15 carbines, they aren't rocket science. Don't get freaked by the technical stuff.

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