18 Inch AR Barrel Questions

AR/M4 AR Technical Discussion
1

I am in the process of building my first AR. I am looking at barrels and am having a hard time picking one. I think I want an 18 inch .223 barrel with a rifle length gas system that’s got a 1/8 twist. I am planning on using a free float rail and comp. I’m not very experienced in this area and don’t know which brands are better than others. If any of you have experience with this setup, what barrels do you like and recommend? I looked for threads on this subject, but didn’t find many. If there are any that you think address this topic well, please point me to them.

2

My AR15 SPR has an 18in barrel setup in 1/8 twist and chambered in .223 Wylde. The barrel is from T-Box but I bought mine through one of their dealers. From what I was told, T-Box barrels come from a Bergara blank. Here is the link: https://www.tbox-barrels.com/product/223-wylde-match-grade-t-box-barrel-bolt/

With 69gr. Gorilla Match Ammo, I am getting sub-MOA results. I am really happy with this barrel.

These pictures were taken when I was zeroing my scope.

3

I’ll answer your barrel question first. But have some comments past the barrel response that I feel are even more important than giving you a good barrel recommendation.

I have had great results with my Ballistic Advantage 18” barrel. Sub MOA when I did my part. I’ve built more AR’s with BA barrels and they are a solid choice. They have a 20% site wide sale going on. If your military-LEO you’ll get an additional 10% mil/vet/LEO discount.

Here is the barrel I used on my SPR. It’s $164 not including any mil/LEO discount. Solid barrel and accurate.
https://ballisticadvantage.com/18-inch-556-spr-rifle-cmv-performance-barrel-ops12.html

There are other options out there, but at $164 for that barrel - you’d be hard pressed to beat that.

If you want an even more accurate rifle, I’d recommend this barrel. I’ve used their SS barrels and they were all tack drivers.
https://ballisticadvantage.com/18-inch-223-wylde-spr-rifle-length-ss-premium-barrel-ops12.html

As far as your M4C “Google Fu”. Try different search criteria. Try searching for “SPR barrels” instead of (18” barrels). An AR with an accurate 18” barrel is often referred to as an “SPR” or Special Purpose Rifle and typically the focus is on accuracy.

SPR barrels search
https://www.m4carbine.net/google.php?cx=010536845846440650985%3Aridd3_u3s3i&cof=FORID%3A10&ie=ISO-8859-1&q=SPR+barrels&sa.x=0&sa.y=0&sa=Search

One hit…
https://www.m4carbine.net/showthread.php?43684-Trying-to-make-a-decision-about-an-18-quot-SPR-barrel

Another hit…
https://www.m4carbine.net/showthread.php?179975-DMR-SPR-rifle-barrels

You said this is your first build so I’ll throw some more food for thought your way. This is just my opine on the matter though…

To me, the barrel is one of the big 3 when you’re building an AR. By that I mean the 3 areas where you don’t want to skimp. Period. (not saying you should in any area, but there are area where you can maybe get away with it.)
My Big 3

  1. Barrel
  2. Trigger
  3. BCG

I’m sure other peoples list may vary, but those area are where I make sure I buy quality.

Also be careful to not fall into a “single part silo”. That’s where you focus on a single part, exclusive of other part. Instead look at the rifle from a purpose perspective. What’s the purpose of the rifle? Identify that and let that drive your parts selection. Thinking about parts you want from that viewpoint will also help you put together parts that are more complimentary.

ETA: I didn’t mention optics in my Big 3, because while purpose definitely impacts optic choice, I consider that separately. I’m strictly talking function and performance of the weapon itself.

So what’s the purpose of the AR?

Sent from my iPhone using Tapatalk

4

I use to think an 18" barrel was cool. In fact, I have two 18" rifles. But, I quickly realized that a good 16" will do anything you need within reason. The question that needs to be answered is what are you plans for this? Strictly a bench type rifle or something you plan on lugging around or using for HD/SD?

5

Sometimes the only reason one needs for a longer barrel (or any other choice) is “I want one”.

Having said that, if you let the forum know of the principal use that you plan for this rifle, the reasoning behind the suggestions can be given.

6

Here you go.

http://www.compasslake.com/index.php?main_page=product_info&cPath=61&products_id=336

7

In 18" you run the risk of getting a Wylde chamber, which you should be aware of. For me, it’s a negative. If you want that chamber and aren’t going to shoot hot 5.56, then fine. I get pressure signs with hot ammo, and only shoot .223 in my Wylde.

8

A .223 Wylde chambered barrel is ideal as it can handle .223 REM and 5.56 NATO very well. You will find that many AR-15 precision barrels have .223 Wylde chambers and 1/8 twist. A 1/8 twist barrel can handle some the lighter loads better than a 1/7.

9

That’s how I was sold it too. However my results (WOA barrel) and reports from my last instructor were that the chamber was problematic with hot 55 gr (WCC), for example, ammo. Popped primers weren’t uncommon. I definitely see spooky bulges near the rear of my brass if I shoot 5.56.

IMO, a good 5.56 chamber is a better choice.

10

I have never had an issue with any 5.56 NATO 55 gr. ammo I have used in my .223 Wylde chambered barrels. The ammo I primarily use is Federal and American Eagle. Even 5.56 NATO 62 gr. poses no problems. One of the barrels is a Ballistic Advantage 16" .223 Wylde 1/8 SPR stainless steel mid-length, Premium Series and the other is a Compass Lake Engineering Recon 16.1" Douglas Stainless (polished) 1:8 twist w/mid-length gas system and .223 Wylde chamber. I even have an older RRA A2 20" HBAR with a 1/9 .223 Wylde chambered barrel that shoots 5.56 NATO ammo very well. My Mk12 Mod 0 has a WOA SS 18" 1:7 .223 Wylde chambered SPR barrel and it shoots any good quality 5.56 NATO ammo I put in it.

11

It appears every barrel has its own personality, but why gamble when you don’t have to. I like 556 chambers and I have enjoyed great accuracy with them. YMMV

If you buy a quality barrel and quality ammo, it SHOULD shoot.

PB

12

Your example of one is absolutely no indication of the Wylde chamber’s suitability for safely shooting 5.56 NATO ammo. It’s just an indication of your barrel and its problems.

Too many people have had success running heavy loads (like 25 grains of RL15 topped with a Hornady 75 seated to 2.25) safely in Wylde chambered barrels. That includes me.

13

Here’s what I don’t understand.

A .223 Wylde and 5.56 are different calibers. (As 5.56 and .223 are different calibers, for that matter.)

Why would you run a different caliber in any weapon? What is gained? Why not run the caliber the weapon is chambered for?

14

I’m not wanting it for home defense. I think my LMT fills that role. I’m thinking more along the lines of a 3 gun or bench rifle. I want to mount a scope on it, not a red dot or just iron sites. I’m also wanting less recoil which is why I am thinking I want a rifle length gas tube.

15

A 16" or 14.5" barrel can also work nicely for this.

The key to a smooth cycling barrel is a properly matched gas system length for that barrel length with a properly sized the gas port.

This means MID length for the 14.5" and longer than mid length (Extended/Intermediate) for the 16".

16

They are not different calibers. For that matter neither are 223 Remington and 5.56 NATO.

The CIP MAP limit for 223 Remington is identical to that of 5.56 NATO, SAAMI has a lower MAP for 223 Remington compared to CIP.

This isn’t as simple as you think.

17

I don’t need it to be simple, but I would like to try to understand it. Are you saying that .223, .223 Wylde and 5.56 are merely different names for the same caliber?

18

Here is a good article to read that explains things fairly well.

https://www.americanweaponscomponents.com/clearing-the-caliber-confusion-223-wylde-vs-5-56-nato

19

Forgive me if you know some of this already. All of what I say below needs to be known and understood to provide a thorough explanation

  1. 223 Wylde is not a cartridge, it’s the name of a chamber (and its reamer) designed by Bill Wylde. This Wikipedia article is a very accurate description of what it is, what it does, and why it came to be: https://en.wikipedia.org/wiki/.223_Wylde_chamber

  2. 223 Remington and 5.56x45 are dimensionally the same exact cartridge. The former is the SAAMI (Sporting Arms and Ammunition Manufacturers Institute) and CIP (Commission Internationale Permanente pour l’Epreuve des Armes à Feu Portatives) designation, the latter is the NATO designation.

  3. 5.56 NATO is a shorthand name used to describe that the 5.56X45 cartridge has been adopted and standardized as a service cartridge by NATO and its member nations.

  4. SAAMI (in conjunction with the American National Standards Institute, ANSI) develops and publishes standards for the testing of small arms and ammunition in the US. Those standards are voluntary, insofar as there is no law or regulation requiring that ammo or arms meet them before being offered for sale in the US. SAAMI centerfire rifle ammo standards are here: https://saami.org/wp-content/uploads/2018/01/Z299-4_ANSI-SAAMI_CFR.pdf

  5. CIP does the same thing as SAAMI with a few key differences. Number one, most countries outside of the US require by law proof testing of small arms and ammo before they are legal to sell. Number two, most of those countries have membership in the CIP or require the use of CIP standards. Number three, many countries require the proof testing be done by independent (and sometimes government owned) proof houses. In other words, manufacturer’s proof is not enough. CIP rimless rifle cartridge standards are here: http://www.cip-bobp.org/homologation/en/tdcc_public?page=1&cartridge_type_id=1

  6. SAAMI and CIP pressure standards for small arms ammunition are not always the same for the same cartridge. That is the case for the 223 Remington (regardless of what you call it here or in Europe). The SAAMI maximum average chamber pressure (MAP) for 223 Remington is 55,000 psi. The CIP MAP for both 223 Remington and 5.56x45 is 4300 bar (62,366 psi). Any European-made 223 Remington ammunition sold here could potentially develop that pressure. Any European-made rifle marked “223 Remington” will have been proof tested based on the 62,000 psi MAP.

  7. SAAMI chamber dimensions for 223 Remington rifles: https://saami.org/wp-content/uploads/2018/01/Z299-4_ANSI-SAAMI_CFR.pdf#page=13 page 68. SAAMI velocity and pressure test barrel chamber dimensions for 223 Remington: https://saami.org/wp-content/uploads/2018/01/Z299-4_ANSI-SAAMI_CFR.pdf#page=13 page 264

  8. CIP chamber dimensions for 223 Remington rifles: http://www.cip-bobp.org/homologation/uploads/tdcc/tab-i/223-rem-170406-en.pdf. CIP velocity and pressure test barrel chamber dimensions for 223 Remington: http://www.cip-bobp.org/homologation/uploads/annexe/annexeiii-en-cr1.pdf (basically take the chamber drawing and apply the tolerances specified in the annex).

  9. US military ammo standards, see chapter 10 page for 5.56 ammo: http://pdf.textfiles.com/manuals/MILITARY/united_states_army_tm_43-0001-27%20-%2029_april_1994.pdf. In summary, max chamber pressure for M193 is 52,000 PSI, for M855 it is 55,000 psi, and for M995 it is 50,250 psi. Presumably those pressures were established in a 5.56 NATO chambered V&P test barrel but I haven’t found a drawing for it. I would assume it’s similar to the CIP test barrel. As an aside, the M197 high pressure (proof) test cartridge develops 70,000 psi which is not quite as high as the CIP proof pressure limit for 223 Remington of 5375 bar (77,958 psi).

  10. As this post https://www.m4carbine.net/showthread.php?55149-5-56mm-NATO-versus-223-Remington-Chamber-Differences points out, there are differences in where chamber pressure is measured between SAAMI and the military. ETA: this seems to support testing equivalency between NATO and CIP: https://en.wikipedia.org/wiki/NATO_EPVAT_testing

PS, your sig line is puzzling.

20

Your example of 1 is worthless. Why are you still posting on this site? You’re an abrasive imbecile. I cited the reports from an instructor with the Sheriff’s Office as to the unsuitability of (at least some) Wylde Chambers with 5.56 ammo… which mirrored my experience as well.