Chose an FN cold hammer forged, chrome-lined barrel this time.

[AbitNutz]

I ended up accumulating enough parts to put together another AR. I decided to go with a 20" barrel, mostly because I didn't have one. All I needed was a barrel. Usually, I would choose my goto Faxon but this I picked up an FN cold hammer forged with a chrome-lined chamber and bore with a phosphate finish at a good price.

I realize that FN is a legendary manufacturer but how good are these barrels? It's an FN-36424, if that means anything to anyone. I know it's not match grade by any stretch but in the hierarchy of good to crap to shit, where does it rank? I'm just trying to manage my expectations.

​

 

[Molon]

It's a chrome-lined, NATO chambered barrel with a government profile. If you use match grade hand-loads, it's going to shoot like a chrome lined, NATO chambered barrel with a government profile. Otherwise, it's going to shoot like mil-spec ammunition shoots.


Colt 6920 Accuracy

If you were given the task of designing an AR-15 barrel profile with an eye towards accuracy, handling characteristics and heat tolerance, along with a length requirement of 16 inches and a weight restriction of 1 pound 12 ounces, the odds are that the last idea that you would come up with would be the ubiquitous 16” government profile barrel with M203 cutouts that is found on the Colt 6920. (How’s that for a run-on sentence?) The profile of the 6920 barrel has more to do with accommodating an M203 grenade launcher than the attributes listed above.



The Colt 16” government profile barrel has a NATO chamber, M4 feed-ramps and is chrome-lined. The barrel employs a carbine length gas system. The stripped weight of this barrel is 1 pound, 12 ounces.

These barrels are typically found with a 1:7” twist but were also produced with a 1:9” twist (AR6920DC).

The 6920 barrels that I have owned have had an “O” stamp at the chamber end of the barrel and some form of a date code stamped just proximal to the gas block journal.

The government profile barrels found on the Colt 6920 tend to show more variation in accuracy/precision from barrel to barrel than heavier profile barrels. The test results shown below were obtained with free-floated barrels.



One Colt 6920 barrel tested from my bench-rest set-up at a distance of 100 yards using match-grade hand-loads produced three 10-shot groups fired in a row that had extreme spreads of:



1.42”

1.19”

1.56”



for a 10-shot group average extreme spread of 1.39”. The mean radius for the 30-shot composite group was 0.44”.







The smallest 10-shot group . . .

The 30-shot composite group . . .

Another Colt 6920 barrel tested under the same conditions as described above produced three 10-shot groups fired in a row that had extreme spreads of:



1.59”

1.55”

1.73”



for a 10-shot group average extreme spread of 1.62”. The mean radius of the 30-shot composite group was 0.54”.



..



Colt AR-15 20” A2 Barrel Accuracy

This Colt 20” A2 barrel started its life on a factory-built Colt 6551. This was a pre-ban rifle, but this barrel did not have one of those evil, havoc-wreaking bayonet lugs. It’s otherwise essentially the same barrel found on the Colt M16A2 and M16A4 as well as on “civilian” variants of those rifles. The barrel has a government profile, a chrome-lined NATO chamber and bore and a 1:7” twist. The barrel stamp reads:

C MP 5.56 NATO 1/7


I installed the barrel on a Colt flat-top upper receiver and free-floated the barrel with a 12” Knight’s Armament free-float hand-guard. I conducted the accuracy evaluation from a distance of 100 yards from my bench-rest set-up using match-grade hand-loads topped with the Sierra 55 grain BlitzKing.

I conducted an accuracy (technically, precision) evaluation of the 20” Colt A2 barrel following my usual protocol. This accuracy evaluation used statistically significant shot-group sizes and every single shot in a fired group was included in the measurements. There was absolutely no use of any group-reduction techniques (e.g. fliers, target movement, Butterfly Shots).

The shooting set-up will be described in detail below. As many of the significant variables as was practicable were controlled for.


All shooting was conducted from a concrete bench-rest from a distance of 100 yards (confirmed with a laser rangefinder.) The free-float handguards of the rifle rested in a Sinclair Windage Benchrest, while the stock of the rifle rested in a Protektor bunny-ear rear bag. Sighting was accomplished via a Leupold VARI-X III with the magnification at 25X and the scope adjusted to be parallax-free at 100 yards. A mirage shield was used. Wind conditions on the shooting range were continuously monitored using a Wind Probe. The set-up was very similar to that pictured below.

The Wind Probe.

Six 10-shot groups fired in a row from this barrel at a distance of 100 yards had an average 10-shot group extreme spread of 1.35”.

A 30-shot composite group had a mean radius of 0.42"

.....

….

 

[AbitNutz]

As I said, the rifle will be put together with parts gathered over time, parts that I picked up at various times were on sale and dropped in my parts bin. If it can do 2-MOA accuracy I think I can live with that.

 

[Near miss]

Does not look too good if you check Molons review..

 

[MK20]

That is a Colt barrel, not FN in the review.

FN shoots well, but not match quality. 2 inches with match ammo is not out of the realm of possibility.

 

[Wizard1183]

That is a Colt barrel, not FN in the review.

FN shoots well, but not match quality. 2 inches with match ammo is not out of the realm of possibility.

How many rounds to get to the 2”?

 

[AbitNutz]

I've found that there are very few true AR "match" grade barrels. It seems like every 3rd AR barrel is labeled match grade. It makes me wonder what matches they're talking about. I'm hoping that this is at least consistent. The fact that it's cold hammer forged and then chromed seems to be a more likely method to achieve this. Maybe not. I'm sure you can achieve absolute shit using any method but I'm somewhat hopeful as a hammer forging machine costs just north of a cabillion dollars.

 

[Wizard1183]

I know the FN Scar17 is very capable of match grade handloads 1MOA 5 shot groups.

 

[jumrobe]

I've found that there are very few true AR "match" grade barrels. It seems like every 3rd AR barrel is labeled match grade. It makes me wonder what matches they're talking about. I'm hoping that this is at least consistent. The fact that it's cold hammer forged and then chromed seems to be a more likely method to achieve this. Maybe not. I'm sure you can achieve absolute shit using any method but I'm somewhat hopeful as a hammer forging machine costs just north of a cabillion dollars.

CHF is the cheapest way to make a barrel…

 

[RUTGERS95]

Does not look too good if you check Molons review..

huh? rack grade barrels above did pretty well

OP, per what you are looking for you need to look at Centurion Arms or take whatever suggestion Molon gives you

 

[Wizard1183]

CHF is the cheapest way to make a barrel…

Perhaps but it’s the longest lasting.

 

[RUTGERS95]

Perhaps but it’s the longest lasting.

I believe the testing points to it being immaterially longer lasting

 

[Wizard1183]

I believe the testing points to it being immaterially longer lasting

Yep I think they’re accurate enough to do whatever you need within range. 800+yrds you’re just shooting in the wind basically but within range it’s accurate for what it is.

 

[MikeMiller]

Not all barrels are equal
Originally M14 Match barrels were just not chrome lined. Most were very good but later Springfield Armory started calling their plain barrels “ Match”. it seems everyone started calling all AR non chrome lined barrels Match after that

A Shaw made Match barrel is not likely to be as good as a Bartlein or Krieger barrel

When it comes to chrome lined. They are designed for combat accuracy, easy cleaning and long acceptable life. Not ultimate accuracy. Remember every variable you add to a weapon system adds one more thing to not be correct.

If you’re dropping into a war zone with M4. Chrome lining is a good thing If your tasked with taking a 200 yard head shot in hostage rescue I would get the best damm barrel I could find.

 

[Shredder58]

I'm a believer in the high quality of the FN CHF Chrome Lined AR barrels. Did a lot of research on these and everything I have read tells the same story over and over about the high quality materials used and the precision and care that FN uses to build these barrels. Also, a friend of mine works at a company that builds the machines for FN that they use for the CHF process and he has nothing but high praise for the precision barrels that those machines can produce.

I recently put together a build that I intended to be a "do it all" gun. Wanted combat grade toughness and quality, able to deliver 1 MOA accuracy, that I could use for either home defense or for DMR/Recce match competitions. I used a FN barrel, 5.56 NATO chamber, CHF and chrome lined, 1/7 twist, and 14.7" length in what they call their "optimal profile". I picked a shorter than average barrel just to add some excitement and so I could push the barrel to it's limits and see what it will do. Was getting just under 1 MOA during range testing with Black Hills 5.56 77gr OTM match loads that they market as D556N9 Mk262 ammo. After 2 range trips to gather Dope at 100 and 200 yards, using weaponized math and no chrono, I figured I was ready for a match. So, I entered and shot a DMR match at Clinton House, SC a couple weeks ago and was very happy with the performance I was getting. I had good hits on targets from 100-700 yards, when many other shooters were having trouble connecting at the longer ranges.

As a disclaimer, I have some years of experience shooting various matches and building and modifying AR and other platforms. Also, I did use many of the tricks used for AR barrel installation that help ensure top accuracy and would recommend similar attention to detail in this area for any AR build where accuracy is the goal.

 

[hlee]

That is a Colt barrel, not FN in the review.

FN shoots well, but not match quality. 2 inches with match ammo is not out of the realm of possibility.

2" groups are a waste of match quality ammunition.

 

[Wizard1183]

2" groups are a waste of match quality ammunition.

How many shots are we talking about? 10? 20?

 

[MK20]

How many shots are we talking about? 10? 20?

I think you might be the same guy from the "how many cow 22 LR make a dead when shooted in head" thread.

 

[Molon]

It didn't take long for the BS accuracy claims to start showing up in this thread.

....

 

[Wizard1183]

What BS accuracy are we talking here? 1moa on a Scar17 5 shot group consecutive can be done…

 

[Wizard1183]

I think you might be the same guy from the "how many cow 22 LR make a dead when shooted in head" thread.

Idk etf you’re talking about Willis

 

[Darayavaus]

I'd talk about the difference between single point cut rifling and button rifling, and why either of them will statistically produce a greater number of more accurate barrels compared to CHF, but some bubba who gunsmiths with a dremel will invariably show up and turn it into an argument.

I think anybody will agree that a good chrome lined CHF barrel will last longer than the soft steel barrels which are typically match grade, especially if the barrel is hot during repeated firings. A good melonite/nitride barrel will also last a very long time, and might potentially be more accurate than chromed CHF. And that's the whole point of military quality barrels. durability first with acceptable accuracy second.

I have several FN CHF barrels in 16 and 20" and they shoot well. milspec well. My 20" criterion chrome lined will shoot better. My faxon barrels tend to shoot about as well as the FNs. My old colt stainless HBAR bbl and Krieger BBls shoot better than all of them.

 

[rpoL98]

I have one of the 20" Criterion CL 4150 barrels, and it shoots very well, my buddies that shoot it call it "a confidence builder". So I bought two more of these barrel recently, getting one of them affixed with the A2 FSB (John Thomas), M5 KAC RAS, for mil-retro looks.

 

[AbitNutz]

With a "parts bin build" I am unlikely to get a tack driver. Although stranger things have happened. So investing in a Krieger barrel and not doing all the backend work to make sure it is aligned and supported and then sacrificing a chicken while chanting the Marine Corps Hymn is pretty pointless.

 

[DocRDS]

With a "parts bin build" I am unlikely to get a tack driver. Although stranger things have happened. So investing in a Krieger barrel and not doing all the backend work to make sure it is aligned and supported and then sacrificing a chicken while chanting the Marine Corps Hymn is pretty pointless.

You shut your whore mouth. Chanting the Marine Corp Hymn guarantees 1 Moa and comes with an resupply of the 64 Crayola ration.

On a serious note the standard for durable barrels on the 'ubiquitous fighting rifle' was CHF, but I never investigated the barrel making process. I also know that chrome lining is not good for accuracy, but handy for combat in nasty jungle environments. I wouldn't say FN is legendary, they have the contract right now or did when I last cared, but the accuracy of the m16 platform didn't suddenly improve when they got the contract.

a lot of ar15/m16 'kit' is hype. A LOT.

LOOKING AT YOU KAC FANBOIS.

 

[Molon]

On a serious note the standard for durable barrels on the 'ubiquitous fighting rifle' was CHF, but I never investigated the barrel making process. I also know that chrome lining is not good for accuracy, but handy for combat in nasty jungle environments. I wouldn't say FN is legendary, they have the contract right now or did when I last cared, but the accuracy of the m16 platform didn't suddenly improve when they got the contract.

News flash: The FN contracts with the US Army for the M16/M4 are for button-rifled barrels.

...

 

[DocRDS]

News flash: The FN contracts with the US Army for the M16/M4 are for button-rifled barrels.

...

See there is so much BS flying about even I can't sift through it all ROFL.

But hey I'm a gunfighter with warfighter kit!!! My rifle is Mil-spec!!

Aka tactical Timmy (mall ninja).

 

[whatsupdoc]

CHF is the cheapest way to make a barrel…

Please share with us where did you get that information from?

It didn't take long for the BS accuracy claims to start showing up in this thread.

....

Cant agree or disagree with that mainly because most cant shoot good groups with an AR regardless of how accurate it is.

 

[Wizard1183]

Please share with us where did you get that information from?





Cant agree or disagree with that mainly because most cant shoot good groups with an AR regardless of how accurate it is.

If you have a decent setup where the gun is locked in and can slide back with recoil? That will test the rifle. If not? It’s the shooter

 

[Molon]

Cant agree or disagree with that mainly because most cant shoot good groups with an AR regardless of how accurate it is.

The 10-shot group pictured below was fired prone off a bipod from my Lothar Walther barreled AR-15. The group has an extreme spread of 0.54 MOA.

...

 

[MikeMiller]

The 10-shot group pictured below was fired prone off a bipod from my Lothar Walther barreled AR-15. The group has an extreme spread of 0.54 MOA.

...

That is a damm good ten shot group from an AR. My Lothar Walther 308 AR10 barrel shoots like that as well. After about six thousand through MK MK12 it’s a 1 moa rifle with great ammo but has sentimental value to me