need help changing a dpms .308 handguard

[struck]

hi I just got a dpms .308 with a 24" fluted barrel and a new handguard, I have changed out handguards on ar15s tons of time but I cant figure out this one?

please help?



thanks in advance for any help.

[DonT]

You didn't say which model so I am going to assume it is the one with the Free Floating Aluminum Guard.

If this is the case the barrel nut is also part of the handguard. You may need a strap wrench to break it loose and I have hear rumours that DPMS uses a small amount of low temp lock tight to keep it from loosening. So you may need a little heat as well. You can call them to confirm.

The barrel nut and handguard form the entire handguard. Usually by having someone hold the rifle, applying a little heat and then use the belt wrench about 2-3 inches from the receiver will break it loose. Then just unscrew it. Should be right hand threads..

DonT

[struck]

yes sorry the free floating alum hand guard, thanks for the info I will give that a try :)

[AngusBangus]

I can think of quite a few ways to heat up the area, but none seem like a good way to treat my rifle. Any suggestions on how to apply heat to the receiver-barrel nut interface?

Thanks,
AngusBangus

[DonT]

Heat gun works best, like is used by model airplane builders to shrink the covering. Gets hotter than a hairdryer.

Live in a hot climate, put it in a car in the sun so the sun beats down on it for a few hours. Use gloves when you pick it up though.

DonT

[AngusBangus]

Thanks for the advice. I have access to a heat gun. And also to a hot climate (MS). One or the other should loosen up the loc-tite I suppose. Can't wait to get back to the states and try it out.

[LouBoyd]

I hold upper receivers laying on their side in the vise of my milling machine. One "jaw" on the top of the Picatinny rail, the other on the surface where the upper and lower come together with snug with a layer of thin cardboard to not mar the surface. it's held very firmly and the upper can take a lot of torque. Of course remove the gas tube with the gas block from the nut and receiver before attempting to turn the nut. I then use a large strap wrench and some resin like used by gymansts and weight lifters between the strap and the tube. You can apply around 200 ft-lbs torque to the barrel nut which is often affixed to a free-float tube. Put the strap at the nut end. A heat gun will help whehter there's some adhesive or not. Apply heat to the nut and not to the receiver so the nut will expand more and loosen it. I've never had one which didn't respond properly but thy can be pretty tight. The nuts are supposed to be tightened between 30 and 80 ft-lbs Whatever in between to make the gas tube line up though a hole in the nut and the receiver. That range may not be quite enough to move one hole. which can require removing a bit of metal from the receiver or barrel nut, or adding a shim.

Get a good strap wrench with at least a 1 foot handle. They come with plastic, cloth, or rubber straps. I've had best luck with the "Rigid" brand with a 1" wide plastic strap. They're available at most plumbing stores . Don't use the kind with a chain and vise grip. They''ll take off the handguard but tear it up in the process. The resin looks bad but washes off.

[Lazerus2000]

one big, one small.

They work well together for breaking the handguard loose from the barrel nut,
especially if you don't have a receiver wrench to hold the upper while working.

When reinstalling, use one drop of BLUE/removable loctite.

Also you can drill and tap a small set screw or two to hold things together in proper alignment.

TWO of my DPMS build R25s had the bipod stud off at an angle and one tube came loose by hand.