SHOULD I FREE FLOAT AN AR15 CARBINE BARREL?

[scooter123]

I'm not an expert but IMO, the accuracy difference between a carbon steel (Chrome-moly, Vanadium, etc) and SS barrel is negligible.
Chrome lining improves durability and extends barrel life but does nothing for accuracy, other than maybe inhibit it. I don't know any accuracy (F class, etc) shooters that use chrome lined but what do I know.
Mechanical accuracy usually is the same whether long or short barrel given the same parameters (barrel quality, weight, etc). I've read debates regarding different barrel materials and rifling methods (ie; hammer forged v. broach cut v. button rifled v. EDM/ECM, etc, etc.) Even heard argument between pulling the button as opposed to pushing the button through the barrel. I guess the same could be argued regarding broach cut but I'm not aware of anyone even doing broach rifling anymore.
FFing a rifle barrel CAN enhance accuracy but I don't think it's a guarantee. Just my opinion.
As to your question, IIRC, there are FF handguards that don't require swapping the barrel nut. They attach using existing delta cap and then the 2 halves are joined using screws. You might try one, that's the only way to determine if it will help but if trying to squeeze every bit of accuracy out of your current setup and it's not what you want, as mentioned, you might try a separate barreled upper as I believe that accurate rifles are that because more so due to quality barrels and triggers than anything else. Once again, just my opinion. Good luck.

Jack there are still barrels being broach cut out there, in some cases they are cut one groove at a time using barrel rifling machines that date back to the late 19th Century. I've been told the reason these antique machines are still held in such high regard is because a single point cut barrel doesn't "string" shots as it heats up, the stresses in the steel in the barrel are so evenly distributed that they balance out.

 

[jack the toad]

Jack there are still barrels being broach cut out there, in some cases they are cut one groove at a time using barrel rifling machines that date back to the late 19th Century. I've been told the reason these antique machines are still held in such high regard is because a single point cut barrel doesn't "string" shots as it heats up, the stresses in the steel in the barrel are so evenly distributed that they balance out.

That's interesting, thanks for posting. I don't doubt there's still broach-cut rifling being done, I just wasn't aware of any like I am of WW2 era (and earlier) sine bar machines using a button cutter.
ETA:
And turning out some pretty darn good barrels too.

 

[Arik]

Jack there are still barrels being broach cut out there, in some cases they are cut one groove at a time using barrel rifling machines that date back to the late 19th Century. I've been told the reason these antique machines are still held in such high regard is because a single point cut barrel doesn't "string" shots as it heats up, the stresses in the steel in the barrel are so evenly distributed that they balance out.

Broach rifling doesn't have anything to do with metal distribution. It's simy a tool that's either pushed or pulled through an object to cut. It has teeth that gradually increase in size

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[lrrifleman]

I think that there are some misconceptions about free floated barrels and accuracy here.

If you look at the competitive ARs being used in CMP and NRA Service Rifle competitions (which until last year mandated the use of iron sights), 99.9% have free floated barrels. Free floating a service rifle moves the critical forward sling swivel from the barrel to the float tube, which minimizes the torque on the barrel and, more importantly, the effect of sling tension on the harmonic vibrations generated with each shot, which does impact accuracy.

Second, you don't need a high power scope to see the benefit of free floating, it can be very evident with irons. Remember, when you are competing with the service rifle, matches are won and lost at the 600 yard line, so the goal is to put all 20 record shots in the 1 MOA X ring, which at 600 yards is a 6" circle!

Now that the NRA has introduced a new rifle category into competitions (AR PLATFORM TACTICAL RIFLE), which will be pitting ARs with barrels 20" and shorter against each other, the issue of free floating or not will be critical.

Being disabled, I can't shoot service rifle matches any more. I now shoot F class matches. F class is much more demanding, in that while the aiming black is still the same diameter, the scoring rings are half the size of conventional targets (600 yard X ring is 1/2 MOA, not 1 MOA, 10 ring is 1 MOA vs 2 MOA, etc), and the rifles need to be more accurate. Basically, your rifle needs to be capable of sub MOA performance, or you are not competitive. A non-free floated rifle would be out of its league, here.

My midrange F class AR is as follows:
- Bushmaster XM15 lower with a CMC trigger,
- White Oak match upper with a free floated 26" Wilson 1:8" heavy stainless steel barrel,
- El Paso Weaver T10 in Weaver rings,
- Versa Pod ski footed bipod.

This setup has demonstrated sub MOA capability, and I am now in the process of developing a thousand yard load for it. One point to keep in mind, is that it can be easier to do a barrel swap with a free float forearm than a non-free floated forearm.

 

[JohnRippert]

Inherent accuracy costs. On a carbine I would just put a good trigger in it and let it go.

 

[marathonrunner]

I think that there are some misconceptions about free floated barrels and accuracy here.

If you look at the competitive ARs being used in CMP and NRA Service Rifle competitions (which until last year mandated the use of iron sights), 99.9% have free floated barrels. Free floating a service rifle moves the critical forward sling swivel from the barrel to the float tube, which minimizes the torque on the barrel and, more importantly, the effect of sling tension on the harmonic vibrations generated with each shot, which does impact accuracy.

Second, you don't need a high power scope to see the benefit of free floating, it can be very evident with irons. Remember, when you are competing with the service rifle, matches are won and lost at the 600 yard line, so the goal is to put all 20 record shots in the 1 MOA X ring, which at 600 yards is a 6" circle!

Now that the NRA has introduced a new rifle category into competitions (AR PLATFORM TACTICAL RIFLE), which will be pitting ARs with barrels 20" and shorter against each other, the issue of free floating or not will be critical.

Being disabled, I can't shoot service rifle matches any more. I now shoot F class matches. F class is much more demanding, in that while the aiming black is still the same diameter, the scoring rings are half the size of conventional targets (600 yard X ring is 1/2 MOA, not 1 MOA, 10 ring is 1 MOA vs 2 MOA, etc), and the rifles need to be more accurate. Basically, your rifle needs to be capable of sub MOA performance, or you are not competitive. A non-free floated rifle would be out of its league, here.

My midrange F class AR is as follows:
- Bushmaster XM15 lower with a CMC trigger,
- White Oak match upper with a free floated 26" Wilson 1:8" heavy stainless steel barrel,
- El Paso Weaver T10 in Weaver rings,
- Versa Pod ski footed bipod.

This setup has demonstrated sub MOA capability, and I am now in the process of developing a thousand yard load for it. One point to keep in mind, is that it can be easier to do a barrel swap with a free float forearm than a non-free floated forearm.

well I learned a huge lesson, if you want a free floated barrel it is better to buy a complete upper from a trusted manufacturer. Yes I realize I can build my own AR upper but what I fear the most is putting together parts from different makers and hoping the tolerances + or - is not to the extreme, less the gun may not function properly. The one thing I like about MFG like Noveske or Windham is when they build an upper, it is hand fitted and tested to ensure it works.

 

[Cardboard_killer]

The one thing I like about MFG like Noveske or Windham is when they build an upper, it is hand fitted and tested to ensure it works.

If you build your own and test it, aren't you also hand fitting and testing?

On another note, one reason to buy an upper from a company is that you can re-sell it and get some of your money back. Uppers you put together yourself have a much smaller pool of buyers, same with used parts if you part it back out.

 

[Arik]

well I learned a huge lesson, if you want a free floated barrel it is better to buy a complete upper from a trusted manufacturer. Yes I realize I can build my own AR upper but what I fear the most is putting together parts from different makers and hoping the tolerances + or - is not to the extreme, less the gun may not function properly. The one thing I like about MFG like Noveske or Windham is when they build an upper, it is hand fitted and tested to ensure it works.

This is not a 1911. All AR direct impingement 556 parts are standard. If you have issues its because of a bad part not because of fitment or tolerance

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[walkin' trails]

What sort of accuracy are you getting from the rifle now. I have several ars, from cheap m4 copies to fairly expensive target rifles, and I find that with all of them, I am the limiting factor to accuracy.

110 percent in agreement.

Of the two modifications the OP asked about, I would say trigger is the more important of the two. The last select-fire Colt M-4 I used to carry had an incredibly crappy trigger and groups, especially off-hand standing were measured in feet. Now, granted, a good part of that lack of accuracy was me and not the gun. When I had to change out the M-4 for an RRA LAR-15 with a 2-stage NM trigger, my groups improved.

That first LAR-15, after 10k rounds, got refurbished and SBR'd to 10.5 last year. It's groups improved, likely because the old barrel was seeing some wear. BTW, that LAR-15 was not free float.

I bought another LAR-15 in 2013 that has the same barrel and trigger group, but is factory free float. Even with a low powere scope, however, I can discern little nor no difference in practical accuracy. Shooting skills and techniques play a great part in rifle accuracy.

I will say that FF certainly is not a bad thing, but solid, steady shooting positions and practiced technique make a greater contribution to accuracy overall.