Floating AR barrels

I've been assembling several "AR style" rifles.

Though I see the value of floating a rifle barrel, I'm a bit puzzled how that technique applies to the AR semi auto.

There is a front sight hanging off "somewhere".
There is a gas block pressed of screwed on as well
Then there is the gas tube that could easily play havoc in regards to any "harmonic tuning".

Is it only to defeat the effects of a tight shooting hold? All slinged up and pulling down hard?

I realize that it is often enough just to make "all factors" the same with every shot.
But it would seem to me that with all the crap hanging off an AR barrel, best results would require some "adjustable tuning device". to get everything to play nicely.

I'm up to three calibres for the ARs Not wanting to add another ;-)

none of those things is a moving part.
unlike say the gas system on an M14 or AK.
and well floating hand guards do work on ARs.
don't over think it or try to reinvent the wheel

So far as I understand it, (having several AR's of various calibers, all but one free floating) it's not about the harmonics, it's more about (A) making sure that all the bits come back to rest in the same place, and (B) keeping any hand pressure on the fore section of the weapon from tweaking the barrel. Especially in the AR-15 with a rifle-length 'stock' barrel, they're pretty skinny, and I can easily imagine them flexing under not-very-much side load from a hand on the fore.

FWIW,
Brian

PS--> on 'floated' weapons that anybody's serious about, they pretty much don't have forward iron sights, or if they do, they're on the tube, not the barrel.
So all that's there is a cut down gas block, and the gas tube.

I am slowly putting together a rifle with this gear:

National Match Service Rifle Float Tube - $12�.�� : Compass Lake Engineering, Best choice of weapons and accessories

I will put a A2 sight on the barrel.

Alberic said:

So far as I understand it, (having several AR's of various calibers, all but one free floating) it's not about the harmonics, it's more about (A) making sure that all the bits come back to rest in the same place, and (B) keeping any hand pressure on the fore section of the weapon from tweaking the barrel. Especially in the AR-15 with a rifle-length 'stock' barrel, they're pretty skinny, and I can easily imagine them flexing under not-very-much side load from a hand on the fore.

FWIW,
Brian

PS--> on 'floated' weapons that anybody's serious about, they pretty much don't have forward iron sights, or if they do, they're on the tube, not the barrel.
So all that's there is a cut down gas block, and the gas tube.

Click to expand...

Some popular shoots around here don't allow "optics", But people still take the shooting seriously. Well, serious enough to stick around until the grill gets hot and the potato salad gets a serving spoon in it. ;-)

Trboatworks said:

I am slowly putting together a rifle with this gear:

National Match Service Rifle Float Tube - $12�.�� : Compass Lake Engineering, Best choice of weapons and accessories

I will put a A2 sight on the barrel.

Click to expand...

TBW That is precisely the device that has my focus. The aluminum rail tubes in various degrees of gaudy just are not my style.

With the popularity of the "magazine box hold". I'm working up a "lower half only" hand grip with cork as handling enhancements. ;-)
I just got the barrel nut in the other day.(CORE Rifle Systems makes a HD unit) Remind me not to grab on to that gas tube! Stainless holds heat for a while. Ouch!

I've got one A2 sight bored to fit out at the end of a heavy barrel. The longer site radius looks good on a rifle, and helps me "see" as well.
Seems like 16" barrels are the rage these days, but I like 'em longer and leaner.

I am going with a 18” Faxon heavy profile.
I am also less concerned about what’s the rage these days.
Looking like a ‘operator’ with the latest and greatest doesn’t do anything for me.
This rifle is getting a walnut stock and hand guard set over that float tube..

Trboatworks said:

I am going with a 18” Faxon heavy profile.
I am also less concerned about what’s the rage these days.
Looking like a ‘operator’ with the latest and greatest doesn’t do anything for me.
This rifle is getting a walnut stock and hand guard set over that float tube..

Click to expand...

I've got a 308 with the Walnut butt stock. Looks and feels might nice!
Got it from Gene at AR15 Wood Stock Sets Home

I'll likely get another if I don't start making them myself from Maple etc. I've got a few blanks.... ;-)

I know this is a stupid question, but what is a floating barrel?

Tom

TDegenhart said:

I know this is a stupid question, but what is a floating barrel?

Tom

Click to expand...

Ahh

This thread could run!

A "floating" barrel on a rifle suggests that there is nothing in contact with the barrel beyond the interface with the receiver.
This may be an extrapolation of "bedding a barrel" where in the goal is to pass a paper thickness between the metal barrel it's self and the "wood work" or furniture of the fore arm. Often in "bedding" an action into a stock, the designer tries to minimize the number of contact points, while also trying to maximize the security of the fixing between the two members, i.e the barreled action and the stock and fore arm.

The AR construction does not have a "stock" to bed with an action. The action, that is, receiver and upper are exposed, unfettered, and unadorned. Simple, like a lever gun. ;-)But there is the issue with holding the barrel in the horizontal plane. This usually means some sort of grip out past the action. A grip that may interfere with the barrel movement on firing. Then there is a sling, if used. It can "pull" on the barrel if not attached elsewhere.

A "floating barrel" puts the hand guard in firm connection with the receiver through the upper attachment (Barrel nut) with all positioning forces taken through the hand guard. Clear as mudd? RIGHT!

Actually, you did an excellent explaining it. Now for guns like the AK47 that use gas assist.

Tom

I will add that the platform provides some additional challenges to the process due to the thin barrel profile.
Barrel whip in ar’s is said to exaggerate any variation in contact points shot to shot.

Or so they tell me- I am a relative novice in ar’s...

I am stuffing one of the piston kits in this build - cancels gas tube effects?
Plenty of rabbit holes to climb into in ar stuff.

Isn’t the formula straight forward here?
Just copy what the top guys at Camp Perry are doing??

I’m a camp perry guy/ highpower shooter, have a high master classification and Distinguised Badge. They now allow quad rails in service rifle but I still prefer the service rifle tubes from white oak, compass lake, and rock river.
Since I do all my own chambering and work I’ve noticed a few things.
With a new barrel on an ar there is a settling in period, it’s really noticeable in the first 10-20 shots but it will still take a few matches before the zeros stop moving.
The reason I bring this up is barrel extension fit to the upper and squareness of the upper barrel socket. I have had a poorly fitting extension/ upper fit cause poor groups and also a small burr or out of square upper.
Make yourself a lapping tool and blue up the upper make sure it’s square so the barrel extension sits flat. Next check the fit between the extension and upper. Most have a .001-.002 clearance which it too much for me. I use thin shim stock to force it up to the top of the hole.
These things have reduced my settling in time and I feel made my gun more consistent.
As far as the gas tube, take the time to make sure the tube is centered and is not dragging on one side of the key or the other. Install the nut, and tube then Take the bolt out of the carrier and insert the charging handle and carrier and feel for drag. You will need a nut wrench that can get around the gas tube for final adjustment.
As far as the gas tube in a free float situation, it can have an effect if it touches. A lot of shooters put stick on wheel weights under the hand guards well if one loosens up and touches the tube it will start shooting erratically also if carbon builds up in the gas tube hole in the upper and in between the upper and barrel nut.
I’ve never seen a piston gun shoot as good as a gas tube gun, even the ones built from the factory. When u add moving parts it causes inconsistently

Thanks for above.
Question for ya-

There is some talk that a free float rig challenges the rigidity if a flat top receiver so a MUR is a good choice or having the carry handle as a bolt on to stiffen up the rig.

Just talk or is there something to this?

MUR: Modular Upper Receiver | VLTOR

We did a test with the push rod vs. gas tube uppers. Everything was identical except for the op system. Shooting from a mount that grabbed the upper rail, and using High Speed video, the gas tube had les movement and shot tighter groups.

Trboatworks said:

Thanks for above.
Question for ya-

There is some talk that a free float rig challenges the rigidity if a flat top receiver so a MUR is a good choice or having the carry handle as a bolt on to stiffen up the rig.

Just talk or is there something to this?

MUR: Modular Upper Receiver | VLTOR

Click to expand...

I think that is just an overpriced answer to a problem that does not exist. My primary match rifle is a blem RRA standard a4 upper. Now granted that I have a WOA 10 moa rail on it and a Vortex scope which im sure adds some rigidity, I don't think its enough to matter if your barrel is truly stress free and free floated.
Even my space gun/match rifle is a standard upper. No need to get fancy with this stuff, quality parts put together correctly with a good barrel and ammo.
About 4-5 years ago CMP and NRA started allowing non usgi appearance parts. Started with quad rails, then optics ( oh the horror, and yes I shoot optics now but earned all my stuff with irons), magpul adjustable stocks and the sport is becoming a tacititard parts race which helps your shooting in no way whatsovever.
Here is a pic of a fellow Cajun and friend AMU shooter Brandon Green, multiple time national champion.. NRA shooter of the year, and this year shot a perfect score in the Presidents Hundred. Look at his rifle, standard a2 buttstock, NM hidden freefloat tube, standard upper, nightforce scope and geissle mount.
Here is a shooter that has at his disposal any equipment or part he wants and that is what he chooses to shoot with. Back when it was still iron sights only we were talking at the ROck River store at Perry and he made the statement " you could but a RRA NM rifle, get a zero, and win Camp Perry, its up to you".
Don't concentrate on the newest gear or fad, concentrate on your shot.

Mil gunsmith, what years were you wrenching on guns at Perry? was it during the M14 years? I came up as a junior shooting a DCM/State Association m14 that was flat worn out. OUr coach would bring seafood and sausage and cook a Jambalaya and Gumbo for the Marine Corps Armorers to work on our guns at Perry each year, was wondering if you were part of that?

I was with the Guard teams back in the late 80's early 90's. My shop partner here is a retired USMC gunsmith from their teams. She last worked Perry about 3 or 4 years ago. We both work for Dept. of Army R&D now.

Well first went to Perry in 91 and every year till 97 then started back up again in 2011

only bad thing about the white oak is the sucker is heavy
my A2 look alike match rifle is almost as heavy as my M14.
looks a little odd with the shark fin grip and no flash hider