Does anyone have experience and/or quantifiable numbers on the difference between accuracy between free float handguards and standard handguards?

No numbers for ya, but my free float hand guard have made a significant difference in accuracy. It just gets REALLY hot when I shoot it a lot.

This is sort of a tag for an answer. I have an upper with a free float handguard that is far better than my old upper with standard handguards and barrel. However, the accuracy gain probably has very little to do with the handguards, as the barrel, sights, and other components are all different.  I am not a good enough shot that  I would notice a difference in the same upper with only the handguards switched.

They did a comparison on non-free float and free float HG on some gun show on the History channel (IIRC) Wish I could remember the name of the show, it showed a military amorer and his shop then they showed them shooting the non-free float with iron sites @ 100 yards and then they shot the free float (National Match) type HG and I think they had about 1/2 MOA improvement @ 100yrds. I looked but can not find the damn video anywhere but I am going to keep looking.

The answer varies and is dependent on barrel weight, length, shooting position and style.



If you have a free floated AR lay it on a table with the side of the FF flat on the table. Now push on the barrel with one finger and you will notice the barrel flexes. It will be less with a short or heavy barrel but it will move.



The FF handguards do not allow any pressure on the barrel so it is consistent.



Shoot the same barrel in a non FF handguard on a sandbag, bi-pod, with pressure on a front mounted sling or any other way the puts any pressure on the barrel and you are flexing it some. The contact of the non FF also effects barrel harmonics.



FF is more consistent which makes it more accurate. Does it really matter for the average AR, I don't think so. For one setup for longer range use with a higher power optic and target barrel...yes it does. If you want the most accuracy from any AR the FF is worth it.

If you sling up with a non free float, at 100 yards you will torque the barrel enough that you can miss a torso target. Same thing bracing on a bench or on cover. It was confusing as hell to me when I first started with a non ff and would shoot slung up at 100 yards and couldnt hit the target.... relaesed the tension and started getting accurate hits. Then I made the swith to a ff and never looked back!

If you always shoot offhand with no sling, you probably wouldn't notice any difference.  Any time you use equipment that puts pressure on the handguards, though, a free-float handguard should help.  Bipods are a big one - if you've got a bipod attached to a standard handguard, any downward pressure you put on it will cause barrel flex to some degree.  In service rifle shooting, the free-float handguards are designed with the sling swivel attached to the handguard and not the bayo lug or front sight tower; this makes a huge difference when you're in the prone position using your sling, because you can put a lot of torque on the barrel if you're slinged up nice and tight.  

If you're just plinking with your basic chrome-lined barrel at 100 yards, you probably wouldn't notice any difference at all.  But if you stretch it out farther, and start looking for real accuracy, free-floating the barrel can really help.

it depends on the gun, if your barrel vibrations with the load your currently shooting happens to lead to no vibration where the handguard attatches, a ff wont make much, if any notable difference since the handguard is not affecting it.  however this changes with different loads and the chances of this are slim, but possible.  also if you use a sling and put tension on it you will notice quite a bit of difference.  Also sandbagging/bipod shooting will bet more accurate and precise.

I have changed out about 50 of them over the years, from standard to free-floated.
I have not EVER seen a case in which the accuracy didn't improve.

In the cases where the change in group size was least, I'd say it made them about 30% more accurate.

In the cases where it changed the most, it went from 2 1/2" groups to 3/4" groups so that would be over 300% better.

If the heat of the FF tube is a problem all you need to do is put a down-grip on it.  For standard FF tubes without integral rails, I take Weaver base
stock and bolt a section onto the hand guard at the 6:00 position for the down grip (and a light if you want one.)
Problem solved.

Funny thing.  I just got back from the range.  I was using my new YHM FF.  noticed at 105 meters I was shooting about 2 inches lower than before with regular hand guards.  I was consistently grouping at 2 inches low, so I simply adjusting my sights and now I'm tits on.  Just thought it was interesting.  Final thought... At 105 meters, not sure how much it affects consistency, but as I learned first hand, it definitely affects POI.

Just to Clarify, since I'm still an AR noob, for this comparison, the FF rail would be 1 piece or 2 piece like this while the non FF rail would be only a 2 piece like this or plastic HG ?

This is probably because your FF tube required removal of your barrel nut.  Thus your gun needs to be resighted in.