I have a plain round type free float handguard that screws into the barrel but. Do I need locktite  on the threads before I screw the handguard in or is it that  not good?

A bit more info might help.

How is it supposed to anchor and/or index onto the barrel nut? Is there a jam nut, does it clamp down with screws, or are you just supposed to thread it on until it stops? Maybe provide the manufacturer and model?

If it is an aluminum tube, and threads onto a steel barrel nut, you should put something between them, if for no other reason than just to prevent galvanic corrosion. Whether that should be a thread locker, or something like the anti-sieze used between the barrel nut and receiver, would depend on how the tube is supposed to get locked down.

yes

Yankee Hill Machine sends this product (but a different brand) with their tubes:



http://www.mscdirect.com/product/details/88545157?cid=ppc-google-*Demo+-+DSA+Restructured_snQzFyoqC__cat%3Amscdirect.com_b_97959250264_c_S&mkwid=snQzFyoqC|dc&pcrid=97959250264&gclid=CI_KvJ-9r88CFQEcaQodfUMIpA



Make sure both the external threads on the nut and the internal threads in the tube are thoroughly degreased before applying the loctite. I use automotive brake and parts cleaner.

Need probably depends on how you will use it.
I don’t Loctite mine, but I don’t use run those weapons in competion or constantly sling up tight.
Also mine (YHM) had anti-rotation screws and lock rings.

This is just a round aluminum tube that threads into a large aluminum barrel nut. It is made by vision defence llc. No rails or anything.  I know it's kind of retro but I didn't really  want rails. It looks like dpms and double star are about the only other ones making them anymore.

They are still popular enough that several other manufacturers are still offering them.



http://yhm.net/accessories/forearms/free-float-ar-15-tubes.html



Damage Industries just came out with pistol, carbine, and mid-length tubes in August.



http://damageindustries.co/index.php?route=product/product&path=72_111&product_id=493



 

Avoid the Loctite.  Not necessary if the attaching parts are properly torqued.  You will not be happy later when it becomes necessary to remove the Loctited parts.

Do you have it in your hands? Does it have instructions that say whether or not to use anything on the threads?

In the absence of manufacturer recommendation, I would probably just use anti-seize grease (the same you used between the barrel nut and receiver) and sufficient torque (probably in the area of 15lbs) through a strap wrench on that mounting system. Not that it needs anti-seize at that low level of torque, but it doesn't need glue, either. I would just put it on there to keep air and moisture out from between the threads, and because I already have it right there and probably got a little on those threads from installing the barrel nut, already.

Out of curiosity, what does that thing weigh? It looks HEAVY.

9" weight is 10.6 oz. I did get an e mail back from where I bought it. They say a little locktite is OK, but they just hand tighten them and never had one loosen up.