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Anybody that says you'll destroy the aluminum frame by heating the tube sufficiently to destroy the loctite is not qualified to make an answer.
If Dunlap said exactly that on a video, I say that their video is wrong.
If they say that it is advisable to minimize heat application, that's a different story- but a distinction with little difference.
Heating the tube in a prudent sensible fashion is no danger except with those frames covered with a decal or paint job that must not be burnt.
I have removed many parts loctited in place with no ill effects on aluminum from the heat.
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I posted plenty of information that is more useful than that AGI video, evidently.
See the pictures of a tube that I removed by heating.
http://www.thehighroad.org/showthread.php?t=275950
My first post there:
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Mossberg tubes are loctited in place by the factory, so if anyone has one without, I would lay money on it being cleaned away by someone at some time without replacement upon assembly.
Dissimilar metals having differential expansion and variance in torque/loosening due to pounding, temperature, vibration, etc..... and... loctite is also for prevention of galvanic corrosion, too.
That being said, the Mossberg tube has an insert at the far end for the barrel retainer screw, and is a complete solid piece of metal inside the tube, minus a threaded through-hole. That is the end to grip with any strap wrench, if you use such a thing. Many other tubes do not have a solid plug on the end, and those would be better gripped nearest the frame, if heat is not to be used. An insert to fill the interior of the tube is HIGHLY recommended in those cases, also, to prevent strap wrench rollover crunch.
Breaking loctite free, if too resistant for the gripping of the far end of the tube, (and with rubber jaw liners for the vise as another tip) may require the use of a small propane torch flame on the otherwise stripped frame at the surround of the tube. The aluminum of the frame will wick the heat around fairly evenly, but keep the flame moving around the outer surfaces, anyway.
Usually there is some residue of old oil and dirt, and will cause an initial fuming with a distinct oily smell, but that will have to be gently burnt off before the temp. may destroy the loctite, but sometimes both happen at nearly the same time.
When the loctite starts to melt, a distinctly plastic-y burning smell and some puffing of fumes will erupt from the joint area, and can burn you quite easily if it pops onto you, so safety coverings and ventilation to minimize cyanide ingestion typical of plastic fumes, if you please. Make sure that the heating continues until the fuming/puffing tapers off, so you know that the loctite is fully toasted. If somebody had a plastic follower installed, about now you'll find it stuck to the inside of the tube, if you didn't make arrangements to hold it up in the tube with a metal rod (away from the heated end).
If you still had the tube end in the vise, you could probably now easily unscrew the tube from the frame, in most cases. The frame is large enough to get a grip for sufficient torque, but you may need heat-resisting gloves, if you are in a hurry.
The first picture is of a .410 with fireman's hose inspired rust and corrosion, along with a little heat damage.
Picture 2 shows the tube removed, with a little loctite still present, but no appreciable thread rusting.
Picture 3 shows the tube hole with remnants of the loctite, but no corrosion. The barrel receptacle is a mass of pure white corrosion product there and in the ejector channel. Dissimilar metal corrosion, with no typical rust-busting compound being effective. Aluminum corrosion is NOT RUST, so even Kroil is not the trick.
Picture 4 tells a valid tale about why loctite may be a big help. If the end of the tube (or the bottom of the hole) is not flat (see that the end is somewhat uneven), then the bottoming torque is not evenly distributed. Any similar situation can be seen to have a greater chance of working loose when the parts are repeatedly stressed, and especially when stressed in multiple manners: recoil, vibration, and so forth.
Mass production has a way of letting through a few parts that are less than perfect, but you will find that a cheap fix may keep them in use enough to satisfy the purchaser, in the beginning.
