Looking to mimic a monolithic rail

[omegajb]

I just picked up a used Sig 556 SWAT that the front handguard rattles , it's not enough to cause any problems since the barrel is free float but it makes my OCD tick.

There are a couple suggestions I've seen one is take a piece of a zip tie and put it near the gas block but that didn't work.

As a test I took the old mount for my Aimpoint and mounted it between the two rails and it stopped rattling.

This got me looking for something slim and low profile to accomplish this but either they don't make one or I'm just not using the right search terms.
I found a picatinny to picatinny clamp (pictured below) which would work, a picatinny to mlok adapter but that option seems to be out of stock everywhere and even this bipod mount if I grind off the nub to the bipod.

Any suggestions on something else that might be a better option?

https://uploads.tapatalk-cdn.com/20201122/99456e90e1423a6d218dad74c07752ea.jpghttps://uploads.tapatalk-cdn.com/20201122/e5372bc7505f60c30a92ed429c51eb76.jpg

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[JoshNC]

The Sig 556 barrel is not free floated. Welcome to the sloppy tolerances and QC/QA of SigSauer USA. Does it move back and forth, side to side, rotate, or all of the above?

[omegajb]

You're right the bottom rail pushes up against the gas block.
It's really the top rail that rattles side to side.

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[JoshNC]

You're right the bottom rail pushes up against the gas block.
It's really the top rail that rattles side to side.

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The gastube interfaces with the gasblock and receiver. The top rail interfaces with the handguard lug on the gastube and with the gasblock. The bottom rail locks up into the bayonet lug boss on the gasblock and with the trunion, held fixed by the front receiver pushpin. If the top rail moves, you could take Saran Wrap, put it on the gastube’s handguard lug, then put some JB Weld or Silicone in the recess for the lug within the top rail, install the rail, install the bottom portion of the quad rail, and clamp across the top of the handguard and the receiver rail. Let it cure, remove the top rail and remove Saran Wrap.

[omegajb]

Thanks, that's a pretty good idea.

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[robbins290]

I used a chunk of rubber off the top of an oil filter to fix the rattle. Stuffed it in the top of the gas block where the top hand guard goes. Snugged it up tight.

[Bimmer]

... it's not enough to cause any problems since the barrel is free float



You're right the bottom rail pushes up against the gas block.
It's really the top rail that rattles side to side.


I don't know if you would see it as a "problem," but it sounds like whatever you're going to do will put tension on the barrel, which might impact accuracy...

[omegajb]

The strange thing is Samson and Troy both make a one piece top rail and handguard that attaches to the bayonet attachment.

Have people noticed a lack of accuracy with these rails?

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[Bimmer]

The strange thing is Samson and Troy both make a one piece top rail and handguard that attaches to the bayonet attachment.

Unless you're trying to build a "precision" rifle, it probably doesn't matter...

I'm just thinking of how barrel/handguard tension is a BFD for the M14 (aftermarket stocks/chassis are set up to adjust the tension), or how the 10/22 guys will adjust barrel tension for accuracy by inserting material between the barrel and foreend of the stock.

If you do this right, you might improve accuracy...