Re: Coating bullets with hBN, with pics!
These guys sell hBN for about half what Lower Friction does. Plus, they're in the US of A. But that's an introductory offer for prospective industrial clients so if you buy from them, don't make a lot of noise that you're a reloader and the one pound you're buying will last you and six of your buddies a lifetime.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: USMCj</div><div class="ubbcode-body">Its not supposed to increase accuracy, its supposed to lower friction, make cleaning easier and give better throat life. </div></div>
Bullet friction has almost no impact on throat life. Throat erosion is caused by --as Bryan Litz puts it -- the "blowtorch effect" of the burning charge and the 'sandblasting' of the gunpowder particulates being driven ahead of the flame front. If bullet friction were responsible, wear would occur down the entire length of the bore and wouldn't be so concentrated near the throat.
But since hBN (or Moly or WS2) will reduce chamber pressures, it also will increase throat life slightly, <span style="text-decoration: underline">if</span> you leave it at that. However, if that's all you're into coating bullets for, you'd get the same benefit for less money and effort by just reducing the charge a by tenth or two.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: magman687</div><div class="ubbcode-body">i just orderd .5 micron do i need to call and have it changed to 70nm or is .5 ok .......5 is what they said is used for bullets but everyone i see is useing70nm? thanks
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The .5 works just fine.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sinister</div><div class="ubbcode-body">...On the other hand boron nitride is supposedly the second hardest substance known to man (behind diamonds).... </div></div>
Being hard doesn't prevent something being a lubricant. After all, ball bearings are pretty hard, aren't they? There's other factors to consider as well.
One trait carbon and boron nitride share is that both exist in multiple forms. Each form is suited to different uses. Carbon atoms arrayed cubically form diamonds. Carbon atoms arrayed in sheets form graphite. Carbon atoms lacking any ordered structure are either coal or soot. Similarly, cubic boron is harder than the dickens and a great abrasive. Hexagonal boron is slicker than owl snot and one of the best high-pressure lubricants known to man.
The moral of this story is, don't try to write with a diamond, don't try to lubricate a door lock with coal, and don't coat your bullets with cubic boron nitride.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Falar</div><div class="ubbcode-body">...Everything I read about coating bullets said that pressure and velocity are supposed to be lowered by coating, requiring you to increase powder charge to get the same velocity with uncoated bullets. </div></div>
Truth, this.