What are the pros and cons of each?
i found this over on ARFCOM it says what i was trying to say with a little more detailAR15.com said:I vote free float. With any standard hand guard, the force applied to the handguard is also applied to the barrel. So, if you use a sling to steady your shot, the force used to pull the rifle into your body will torque the barrel. This is true whether your sling is mounted to the forearm or the front sight. If you use a "sling thing" mounted to a free float system you can pull on that sucker has hard as you want and not move the barrel.
If you don't use a sling like that, (I don't. I have a single point sling.) It still applies if you use a rest or a bipod. You may exert some force on the forearm that puts force on the barrel. With a FF system this won't happen.
Also, you might want to mount optics on the rail. If you ever want to add NV behind a red dot or holo sight, you can't hold zero. Or, like me, you might like the sight as far forward as possible. I mount my EOTech on the hand guard. Mounting your sight as far forward as possible has many advantages that have been covered in many threads before.
There are too many reasons why a FF sys is better than a standard railed hand guard to buy the standard based only on price.
To modify Troy's sig line...
"Go Free Float or Go Home!"
Today's free-floating AR handguards are intended to do more than just provide a place to hold on to. Another development we can thank NRA High Power shooters for, free-floating handguards primarily enhance accuracy. Plus, with the addition of MIL STD M1913 rails, they also allow the attachment of mission-specific accessories like lights, vertical foregrips, bipods, IR illuminators and white lights. This allows an end-user to quickly and easily configure his weapon to fit his specific needs. In doing so, it increases the flexibility of the weapon and the survivability of the operator.
Flattop uppers allow a variety of optical and iron sights to be easily mounted.
Two quality designs that I like are LaRue Tacticals (due to its secure attachment method) and PRI (due to its shape). If you'd like to retrofit a fore-end rail system onto your weapon in place of your existing handguards, SureFire offers a system recently adopted by the DEA and FBI. A two-piece design, it locks in place securely via set screws. While it can't enhance accuracy compared to a free-floating design, the amount of degradation is not significant enough to matter in the real world.
Not unless you are shooting long distance competition or varmints. The Army just did a survey on the M-16/M4 platform to see if replacement with a new weapons system was necessary, the conclusion they came to was the more crap hung on a M4 the less reliable they became. So if you just want a free float tube go for it but the rail systems can be detrimental to reliability if you mount more than a fore grip/flashlight on them. These were the Army's findings not mine so flame away.What about accuracy? if freefloat worth it? with max shooting 300 meters?
The VLTOR CASE V system (Mike can show that off) is lighter than most standard FF Railed forends and more versatile.
I would imagine that the Army's tests were NOT with railed FF tubes (standard M4/M16 doesn't have a FF tube). It would make sense that a tube that contacted the barrel would cause accuracy issues when more stuff was hung on it (weight changes the pressure points, influencing accuracy). If they were using a FF tube, I would bet that accuracy wouldn't change much, if any. Added weight wouldn't have an influence on the barrel at all if the forend isn't touching it.Not unless you are shooting long distance competition or varmints. The Army just did a survey on the M-16/M4 platform to see if replacement with a new weapons system was necessary, the conclusion they came to was the more crap hung on a M4 the less reliable they became. So if you just want a free float tube go for it but the rail systems can be detrimental to reliability if you mount more than a fore grip/flashlight on them. These were the Army's findings not mine so flame away.
The VLTOR is listed as almost a pound and the 2 peice MI FF is listed as 11oz.I've got 2 MI 2 piece FF rails installed on a 20" and 16" AR. The weight of the MI's are a bit disturbing but the flexibility to move the add-ons around is worth it. They are however very easy to install and lock up very tight on the barrel nut. MI also provides you with a monolithic upper rail which was one of the 2 reasons I went with them over their more expensive cousins.
For a sub-300m gun.. you might look at the YMH light weight rails. You would have to remove the flash hider and FSP (both are stupid easy to do) to mount the one piece rails like YMH, LaRue, Troy... ect.
The SureFire rails while not free float and not providing a monolithic upper rail are fairly solid. I wouldn't mount optics on them and expect absolute retention of your zero, but for lights, VFG and the like they are more than acceptable, just a bit proud of their name and the price reflects that. Again, I've got a set of these on one of my AR's, moved it across 3 different AR's since purchase a few years ago and don't have any serious issues with them.
Bare in mind there are several other options that will FF the barrel and still give you the advantages of forward rails and weight reduction. The VLTOR CASE V system (Mike can show that off) is lighter than most standard FF Railed forends and more versatile.