I am about to start on my 6th build. Yes, I have the AR bug bad.
But my question is whether free floating actually has any value to accuracy.
Regular: Upper >> Barrel nut >> Delta ring >> Hand guard cap >> Barrel
Free Float: Upper >> Barrel nut >>
Both must hold on to the barrel nut (factory or not) and must connect to either the wobbly upper or not.
So I don’t see how free floating helps with accuracy since ultimately you end up holding the rifle via the hand guard and if you have any wobble in the upper you could already be off by 1 MOA.
Free floating improves accuracy definitely. FF forearm is isolated from the abrrel, whereas regular build entails front end of HGs contacting the barrel. Any sling pressures get transferred to barrel ,barel harmonics are impacted, etc.
FF has been a staple of the HP crowd for eons, and they wouldn’t go through those efforts if there were no benefit.
Free floating can, and on an AR usually does, help in two ways:
Eliminating any variable pressures on the barrel, like sling or bipod, to avoid bending the barrel and changing POI relative to how you zeroed the rifle; and
Eliminating interference with barrel harmonics so that the barrel vibrates the same way with each shot.
The amount of benefit will depend on how stiff the barrel is (largely a factor of its length and diameter) and how you use it. Someone using a 1" bull barrel the exact same way for each shot might see relatively little benefit, while someone using a pencil barrel in varied positions, with and without sling pressure/bipod/barricade support might see a major benefit.
It’s notable that many non-AR rifles, such as the M1A and many boltguns, will get best accuracy with only part of the barrel floating, and the rest bedded to a rigid stock. That’s not generally practical with an AR, while the AR design makes it fairly easy to free float the whole barrel, so the AR recipe is usually to be fully free floating.
By wobble, are you referring to the play between the upper and lower? I’m not sure where 1 MOA came from, but as your sights are attached to the upper, not the lower, you can disregard it.
This is largely correct, but both of these posts talk about accuracy. That’s not really what free floating addresses. A free float tube is about repeatability; it removes (well, minimizes) variables.
I’ll use your example of highpower shooters. If sling tension was consistent, then it could be accounted for. “Cranking down on my sling moves POI X amount. I’ll adjust my sights X amount.” But its not consistent. The barrel may still have the same inherent accuracy, but its getting aimed at a different point each time. By using a FF tube, you remove the varying influence of the sling on the barrel.
This applies to anything that would apply a force on the barrel through the non-FF handguard: using a bipod, resting the handguard on a support, getting a really firm grip on the gun, etc.
If you will never use a sling to provide support and you don’t intend to shoot past 100-200 Meters a free-float tube or rail is an expense you should probably forego for an optic that will help you point better, or ammunition.
I have also read that a FF rail can increase bolt life under certain circumstances like FA fire with lots on the rails. It keeps strain off the barrel which can affect the alignment of the barrel extension.
"I beleive that even a steel bbl nut affixed onto the rail will act as a heatsink to some extent.
The advantages to the FF system (depending on mount type) can allieviate the pressure on the barrel from a vert grip etc.
All weight on the barrel will contribute to forcing the barrel/barrel extension slightly out of alignment - thus forcing more pressure on one side of the bolt - especially on unlocking the locking lugs of the bolt will have unequal pressure exterted upon them - and thus lead to reduced bolt life.
With a more uniform pressure/lock, this then decreases wear and inturn leads to great life and reliability. Additionally this is another place where thin barrels with suppressors suffer greater bolt failure than thicker barrels.
Crane had a metric ton of data on this stuff for those with access who are curious."
Studying bolt stress was part of how Vltor came up with the MUR upper. The wanted a flat top that reduced receiver flex so the bolt went straight into battery all the time.
Depends what distance you are shooting. 100 yards or less, you’re fine with a hand guard. Heck even past 100 yards you’re fine with a hand guard unless youw ant to put two bullets through the same hole. There is a difference between accurate and combat accurate.
What I am going to say has already been said, but I will say it anyways The reason to free floating barrels is so that there is only one point of contact at the barrel nut. The hand guard gas block creates a 2nd point of contact.
If you are pulling on your sling and your sling is attached in some way to your barrel, that has an affect. If your hand guard is resting on a sand bag and your handguard attached to your barrel, that has an affect. In short, someone used the word repeatability, and that’s the perfect word to describe it. With a free floated barrel you will get the most repeatable results. Free floating won’t turn a chit barrel into a .001 moa barrel.
For free float, I like the Daniel Defense MFR (available in 9 and 12") or the Troy Alpha rail (available in 7-15"). Both are free float with a continuous top rail, and modular side and bottom rails.
The reason to free floating barrels is so that there is only one point of contact at the barrel nut. The hand guard gas block creates a 2nd point of contact.