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Posted: 6/2/2008 8:36:14 PM EDT
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I know what it is and the reasons for doing it(accuracy etc), but i'm trying to grasp the concept here. I have standard quad rails using my delta ring and the ring right below FSB I can't understand how the rails which do not touch near the FSB hold accessories better then something that is hard mounted to the barrel. Wouldnt't the VFG cause give? It just seems that holding the rails would make it move - am i putting too much emphasis on the word "float" can someone help me graps this? All i want on my rails are the VFG and Tac Light- |
It ain't a matter of stronger, its a matter of not putting a load on the barrel. The 'free float' concept is that the barrel is held on by the locknut at the chamber and nothing touches it all the way to the muzzle. That way one can't put a side load on the barrel from, say a tight sling wrap around your arm. It allows the barrel harmonics to operate undisturbed. |
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I think I'm not asking my question right- I understand the benefits of taking the rail off the barrel, but how can it be "stronger" to mount optics etc then the non free float- it seems the strengh of having the quad rails attached top and bottom would hold accessories easier- i understand the stress on teh barrel because of this- i guess, i'm thinking, stick a pencil through the bottom of a styrofoam cup- its not touching the drinking part is free floating- it would move around- but if the cup had to ends and the pencil came out the top- it wouldn't move no give to move because its through the styrofoam top and bottom EDIT: costeve- i just re-read your post- thanks- does a FF move around the barrel- does it "sway" when holding the VFG? 1 more thing- the mounted FSB- i'm assuming its ok to leave that on teh barrel rather then going with rail mount front sights? |
And to isolate sling tension in the sitting/kneeling /prone positions from the barrel in CMP Service Rifle shooting. A tight sling on a beefy shooter can pull 3 MOA or more on even target weight barrels. This was allowed by a rule on the books allowing the forward sling swivel to move back a bit. The front cap of the handguards then had the swivel lug welded to it and the tube. There is a slight gap, about 0.01" between the FSB and the front cap. |
But most FF tubes are not all that stiff. and any forend pressure can cause a shift in POI. As the rear of the tube is fixed, it can be considerable. But if you are using optics for under 100 yards, it shouldn't be an issue. And if you are not putting excessive pressure on the forend for long range work, it also shouldn't matter. |
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The stronget rails are actually manufactured along with the upper receiver out of a single billet of aluminum. This is the idea behind LMT's Modular Rail Platform (MRP). The MRP is available in both Rifle and CQB length. I have a CQB length myself and like it very much. If you don't have an MRP and want the best accuracy, I recommend your front sight be attached to the free floated barrel for best accuracy, rather than being mounted on the top of the rail. As mentioned in a previous post, the front sight can sway along with the front of the free float. 
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There is little or no difference between a FF and non-FF rail in terms of the accessories mounted on it. Both can be twisted out of position with enough force. The difference is that the FF rail will not then apply that force to the barrel. No rail system is ideal for mounting optics (even monolithic uppers will have some flex) and the optic should never bridge the gap between the receiver and the rail. |
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