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Thread: Heat Shrink Tubing on castboolits

  1. #1
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    Heat Shrink Tubing on castboolits

    I noticed a couple of years ago that there are now some pretty tough types of heat shrink tubing. I bought some made of very slippery and pretty tough material. I was wondering if there are any material science folks here that know about the different types of heat shrink material and if any could possibly be used for "patching" boolits. OR if anyone has been crazy enough to actually experiment with it.

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    Heat shrink tubing isnt that tough. Most of automotive stuff has rubber band like consistency or feel. The better stuff we use for aircraft are considerable tougher and more like a resin or molten plastic. Its harder but is considerably thicker and due to that would make a better bullet than it would be coating. Some of the tubings we have would add about a 16th of an inch. I have seen liquid electrical tape, but its not authorized at work so i have no experince with. We have several different teflon tapes, but due to their thickness it would be hard to patch. They just teflon though.

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    The one I am fairly sure would stand heat really well is Teflon. But I bought some a few years back with the thought of using it in this way, and it was both too thick and too uneven in thickness from one side to the other. It would certainly have put the bullet's centre of mass several thousandths off-centre at the least, and that is fatal to accuracy in a rifled firearm. It could be different with smoothbore slugs, or what is available now may be better.

    There are a couple of points to watch for. Teflon gives off dangerous gases at high temperatures. I think this is only likely to matter in an indoor range. Also with any kind of heat shrink tubing you would have to use slow oven heating to shrink it. If it shrinks more on one side than the other, that side will be thicker.

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    It definitely won't like being shoved down a rifled barrel at high velocity, it would be shredded very nicely, and because you would have to use a considerably undersized boolit to allow for the thickness of the heat shrink your accuracy would be "interesting" to say the least!

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    Some kinds, probably, but paper patches are shredded very nicely, and all to the good if they stay where they are meant to be until the bullet exits the muzzle. Teflon has a melting point exactly the same as lead, and a much lower coefficient of friction. It is frictional, not combustion heat that would cause any problem, and it appears not to do so with bullets coated with teflon in other ways. I think thickness and unevenness of thickness are the only things against it.

    https://en.wikipedia.org/wiki/Teflon-coated_bullet

    I've got Clyde Williamson's "The Winchester Lever Legacy", which includes his patent certificate for wrapping a bullet in teflon plumber's tape, applied on top of lube in grooves, which is then melted. I used to belong to an association which banned the practice in classic shooting events. I have tried it with .40-82 and 8x60R, and could distinguish no difference in the results. But then, I wasn't trying for extreme performance. It might have been either better or worse if I had been. Or much the same.

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    Excuse my ignorance but does anyone manufacture Teflon coated bullets? Can lead even be coated by Teflon (other than wrapping Teflon tape around the bullet?) Could Teflon be added to powder coat? Does normal powder coat have anywhere near the slipperiness of Teflon? If I am going to make the very best 22lr bullets the world has ever seen I will need to know these things. lol.

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    The old federal Nyclads ( later Smith and Wesson or is that reversed?) were Teflon coated soft lead intended for self defense ammo. This ammo did well and performed good. The whole bullet was coated similar to the PC high tech coatings of today.
    I have heard of Teflon tape being used to patch bullets. The issues I see are its soft and slippery so getting a good consistant wrap will be hard to do. It tears easily so that will be a problem. finding tape in a wide enough strip to go from ogive to base with fold under may be tricky also. Last is its durability thru the bore and release at the muzzle.

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    I've used large diameter heat shrink to assemble projectiles for my 40mm. I've never tried it on anything smaller than that though. It held up well enough at 270 FPS, but I can't say I ever pushed it harder than that.
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    Quote Originally Posted by Traffer View Post
    Excuse my ignorance but does anyone manufacture Teflon coated bullets? Can lead even be coated by Teflon (other than wrapping Teflon tape around the bullet?) Could Teflon be added to powder coat? Does normal powder coat have anywhere near the slipperiness of Teflon? If I am going to make the very best 22lr bullets the world has ever seen I will need to know these things. lol.
    I don't believe anybody now does, largely due to unwise marketing and media hysteria. Some member of the intellectual classes marketed pointed solid brass bullets with Teflon coating, and the media ran away with the idea that they were better than ordinary bullets at penetrating bulletproof vests - as indeed they were, thanks to being hard and pointed. So the label "cop-killer bullets" sold papers.

    You have implanted an intriguing thought. I don't know if teflon lacquers are durable enough, or have more than advertising-purposes amounts of the stuff in them. 1.6 micron teflon powder is fairly cheap on eBay, but I don't know if it could attach electrostatically. A domestic oven wouldn't melt it, even if you fancy the fluorocarbon emissions. But in the late 1990s the wonder of the age, which we don't hear so much about now, was a mixture of carnauba wax and molybdenum disulphide powders, applied in a tumble polisher. That probably could be done with teflon powder. Then you would only have to work out a way of determining whether anything else would have performed worse.

  10. #10
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    Virgin Teflon degrades to a toxic form at 750F. Several OP have used it for wrap/lube and it sort of works. Not for me.
    Whatever!

  11. #11
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    Quote Originally Posted by NoZombies View Post
    I've used large diameter heat shrink to assemble projectiles for my 40mm. I've never tried it on anything smaller than that though. It held up well enough at 270 FPS, but I can't say I ever pushed it harder than that.
    Everybody should have one, I'm sure. But is it smoothbored? That would be a lot more tolerant of the bullet's centre of mass being off the bore axis, and hence of unevenness in thickness of the coating.

    The melting point of both teflon and pure lead, 327°C is 620°F. Lead can reach that in bullets, but I am hopeful that the reduced friction would prevent that, and Federal don't seem to have risked their reputation on something that would happen 130°F over the temperature at which it melts. Run a lead bullet at a velocity producing that temperature, and see what happens.

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    Quote Originally Posted by Ballistics in Scotland View Post
    Everybody should have one, I'm sure. But is it smoothbored? That would be a lot more tolerant of the bullet's centre of mass being off the bore axis, and hence of unevenness in thickness of the coating.
    Actually it's rifled (registered as a DD here in the US) but the thickness variations are a much smaller percentage of overall diameters. When you're talking about a bullet that's .308, a variation of .002 is a lot more significant than when the projectile is 5 times that diameter. I'm sure the lower velocity helped me out as well. But my projectiles landed where they should have without any more deviation than I get with factory rounds.
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    Just what I thought, the other way around, about using the technique for a .22. With those, inconsistency in any kind of coating assumes exaggerated importance.

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    Black Talons were the so called cop killers. Now they are called Ranger bullets without the black coating. Win still makes some of their rifle bullets coated with the same coating. It is on their Supreme ballistic tip.

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    One thing that might work would be to mix some graphite in with the PC. We mix it with epoxy to put it on the bottom of boats to make them slide better acrossed mud and plants.

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    Quote Originally Posted by tomme boy View Post
    Black Talons were the so called cop killers. Now they are called Ranger bullets without the black coating. Win still makes some of their rifle bullets coated with the same coating. It is on their Supreme ballistic tip.
    A good Chicken Little catchphrase is too good to use only once. Black Talon bullets were something completely different - a jacketed hollow-point designed to open out into an array of sharp prongs. It had a black oxidised finish, and was widely misreported as being teflon or molybdenum disulphide coated, and misreported as being significantly different in its action from any other hollow-point that works. It would surely be worse at penetrating ballistic nylon, just as in the world of advertising if it's high in something, it's low in something else.

  17. #17
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    Correct me if I'm wrong but I think the shrink wrap coating on bullets is being used on muzzle loader bullets Called Power Bands or Power Rings. Something like that. The wrap covers the bearing surface.

  18. #18
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    Quote Originally Posted by tomme boy View Post
    One thing that might work would be to mix some graphite in with the PC. We mix it with epoxy to put it on the bottom of boats to make them slide better acrossed mud and plants.
    Been there....done that.......years ago when we all were developing the BBDT coating process.

    Graphite KILLS the static electricity needed to make the powder adhere to the lead until you cure it.

    I even had a hard time getting it to stick with the correct way of PC'ing...........ESPC guns.

  19. #19
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    The brass bullets the poster was referring to were KTW rounds, long before the Black Talon name ever came along. I had the opportunity to play with a few of those before they became the victim of the press.
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BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
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