Disassemble free float tube handguard

[tangolima]

Got this AR with my old style fiber glass free float handguard tube. It is a few inches too short to my liking, and it is lack of rails. Plan to replace with mlok product. However I have heck of time trying to take the old tube off. Tried to torque it off with strap wrench to no avail. Did I miss anything? Any tips is appreciated.

-TL

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[jcj54]

1) remove scope
2) remove upper from lower and remove bcg and charging handle
3) using clamshell vise blocks clamp in vise
4) use heat gun on barrel nut area of handguard/float tube
5) use heavy duty strap wrench with rosin powder on tube close to barrel nut

[tangolima]

Thanks. I thought of applying heat but wasn't sure. So the tube has been glued to the barrel nut?

-TL

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[jcj54]

Most likely

[Shadow9mm]

You sure its fiberglass not carbon fiber.

jcj54's advice is on point!

[tangolima]

You are right. Carbon fiber.

-TL

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[10-96]

I don't know about that particular handguard, but I do recall seeing some being sold with either epoxy or some other heck-for-stout glue to glue the sleeve to the bbl nut. If you can get to all the set screws on the gas block, I'd pull it and the gas tube out and just replace both of them, especially since whatever tube you go with likely won't mate up with that bbl nut.

[tangolima]

The gas block and tube will need to come out. The GB is pinned so it may require some doing. Gasing is almost perfect with this rifle. I probably will reuse the parts.

-TL

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[tangolima]

I finally gathered the tools and gave it a real push. It didn't work. The tube simply refused to budge. With no intention to reuse the carbon fiber tube, I hacksawed it where the barrel nut is. I was glad I did. The glue applied to the thread, I doubted I could break that bond without breaking something else first, even with enough heat.

The pinned gas block was pretty much "welded" on the barrel by years worth of carbon deposit. Couldn't get out the gas tube either, so I hacksawed it in half and managed to wriggle the pieces out with vise grips.

The barrel nut has 20 holes. I thought my 3-pin wrench would fit. Almost but it didn't. I will need to order another for that. Will see.

It is a high-mileage rifle I bought from a local guy. It still shoots ok. I will need to put in a new barrel sooner or later.

-TL

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[10-96]

Tangolima- If you're already that deep into it, you might as well go at that nut with a ruther big pipe wrench providing the receiver is well secured. You're well past kid gloves and niceties at this point. Lol

[tangolima]

Good point. I will give it a try. Hate to spend money on tool that I only need to use once.

-TL

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[tangolima]

The pipe wrench did it, although there seems to be some sort of thread locker on the thread. Thanks. It saved me $40.

I'm not quite out of the woods yet. The gas block and muzzle device are all stuck in place. I thought I didn't need to worry about them, and I'm wrong. Looks like I will have to heat them up to break them loose. But I don't want to over do it and screw up the barrel's heat treat.

Any suggestion?

-TL

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[FrankenMauser]

Any chance the pieces might be salvageable with some work?
I have an AR22 that I call the "Garbage Rod" that was built from parts literally out of a dumpster, combined with the lowest grade garbage I could find, and some additional parts out of a dumpster. A truly garbage-tier FF tube might be better than the sponsored FF tube tri-rail that I have now.

[tangolima]

I think so. That's what I'm trying to do. It has pretty ok muzzle brake. There is still have some life left in the barrel. Not care much about the pinned gas block. Gasing is almost perfect though. Worst case is to give up the whole barrel assembly and put a new one on the upper receiver.

-TL

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[stagpanther]

Be careful when going full Rambo on getting the barrel out--I'd think about which is more valuable--the barrel or the upper. Gall the threads on the barrel and that's pretty much it for it (unless you have a good friend with a good lathe). I have cut and recrowned a muzzle myself using hand tools, but the results still weren't as good as what a good lathe can do IMO. Is this your AR 10 project by any chance? I have a carbon handguard on a blowback PCC and love the thing--I can spin it on/off in seconds for a quick barrel change. It's secured to the nut by some kind of epoxy/glue but also has a set screw of some sort. Does the gas tube from your block pass through a hole in the barrel nut by any chance?

[MarkCO]

That was an old School Carbon Fiber HG, DPMS style barrel nut and the CF was epoxied to the barrel nut. The problem you had was the problem I solved when I came out with the Carbon Feather handguards for AR15 and AR10. The CF tube was epoxied into an aluminum adapter that threaded on to the outside of the DPMS style barrel nut, that was then held solid with a jam nut from the backside.

Strap Wrench with a rubber insert was about the only way to get them off. Heat would not have helped at all. Too much aluminum and CF to get through to get to the receiver extension.

DPMS recommended Loctite. You should be able to use a heat gun (won't touch the HT on the barrel) for the comp and gas block IF they used Loctite. Is there color to the thread lock on the receiver extension? If yes, mineral spirit and a metal brush will, with some effort clean it up. If it appears clear, it might be Rockset. That takes hot water and impact to loosen (gas block and comp) and you will have to use hot water and a metal brush and a lot more elbow grease to clean that out of the thread root.

[tangolima]

Originally Posted by stagpanther

Be careful when going full Rambo on getting the barrel out--I'd think about which is more valuable--the barrel or the upper. Gall the threads on the barrel and that's pretty much it for it (unless you have a good friend with a good lathe). I have cut and recrowned a muzzle myself using hand tools, but the results still weren't as good as what a good lathe can do IMO. Is this your AR 10 project by any chance? I have a carbon handguard on a blowback PCC and love the thing--I can spin it on/off in seconds for a quick barrel change. It's secured to the nut by some kind of epoxy/glue but also has a set screw of some sort. Does the gas tube from your block pass through a hole in the barrel nut by any chance?

It is not the AR 10. That one has been set aside waiting for the upper receiver to be returned. This one is an original Alexander arms AR 15 in 6.5 Grendel.

Looks like people all wore belt and suspenders back in the day. Everything was installed with no intention to be disassembled for replacing parts.

I plan to pull the barrel from the upper receiver and put in a new barrel, which I will have to do sooner or later. The old barrel may be salvageable with some doing. The comp and gas block will put up a fight. I'm going to defer it some other time.

-TL

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[tangolima]

Originally Posted by MarkCO

That was an old School Carbon Fiber HG, DPMS style barrel nut and the CF was epoxied to the barrel nut. The problem you had was the problem I solved when I came out with the Carbon Feather handguards for AR15 and AR10. The CF tube was epoxied into an aluminum adapter that threaded on to the outside of the DPMS style barrel nut, that was then held solid with a jam nut from the backside.

Strap Wrench with a rubber insert was about the only way to get them off. Heat would not have helped at all. Too much aluminum and CF to get through to get to the receiver extension.

DPMS recommended Loctite. You should be able to use a heat gun (won't touch the HT on the barrel) for the comp and gas block IF they used Loctite. Is there color to the thread lock on the receiver extension? If yes, mineral spirit and a metal brush will, with some effort clean it up. If it appears clear, it might be Rockset. That takes hot water and impact to loosen (gas block and comp) and you will have to use hot water and a metal brush and a lot more elbow grease to clean that out of the thread root.

I didn't see any sign of thread locker other than the stuff on the upper receiver barrel nut thread. It appears clear / white. It wasn't a problem. I managed to undo the barrel nut with pipe wrench.

The gas block and comp may have been locked in place by excessive carbon deposit. The mild heat I have tried didn't help. The comp has compression washer. I may have to carefully hacksaw it away to relief the tension.

Any chance the gas block was a thermal fit? I wouldn't be surprised if it is. Maybe I can rest it on vise jaw and hit the comp with cushioned hammer blow to impact the gas block off the journal?

-TL



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[georgehwbush]

remember how hot a barrel gets from firing a mag full. and don't be scared to heat it up. "just not glowing hot"

[stagpanther]

In the early days of the Grendel Bill was pretty proprietary about his wonder cartridge; wouldn't surprise if that extended to his firearms.

[MarkCO]

I've not seen a Thermo-Fit GB, but maybe.

Yeah, if it was Bill, he certainly did not like folks messing with what he built. I can see Rockset as a definite possibility with that info.

[tangolima]

Muzzle device is out. Visegrip padded with leather adjusted the wrong attitude. GB is still fighting on. It has resisted some serious hammer blows.

It is a pinned GB. I'm afraid the drilling and pounding in the pins may have raised burrs inside, locking the part in place. I have time.

I'm thinking about the barrel vise that I haven't used for a while. Clamp the barrel there and wrench the GB loose.

-TL

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[jcj54]

If the pins are out, clamping the barrel and applying some heat and then Kroil or other penetrating oil may do the trick. Odds are the powder residues drew moisture and caused some rust.

[tangolima]

Heat first then oil? That's will cause some sizzling in the "kitchen".

I will try that before going mini nuclear with the barrel vise. I'm prepping for it at the moment. A few drops of kroil a day for a week to soften the "enemy's defense".

Full nuclear would be cutting disk on foredom (you think Dremel is bad huh) to slice it. One slice will relief much of the tension. 2 slices will sure warrant unconditional surrender. I have put the GB on notice.

-TL

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[Unclenick]

If you are not in a great hurry, get the thing wet with Gunzilla and just wait a few weeks. It penetrates well and breaks down rust and carbon bonds, both.