Talk to me about hex boron nitride

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Roadkill2228

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Pretty much what the title says. You could also include findings about moly and tungsten disulfide. The copper oxide (lubalox) on Winchester combined technologies could be included as well. But hbn sounds like the final winner for coatings to me. Reduces friction, greatly reduces extreme spreads, has a virtually limitless thermal ceiling (like if it got hot enough to affect this stuff which is a ceramic, your barrel would be wrecked for other reasons). Mixed reviews on whether or not these coatings can allow for higher velocities. All things being equal they actually reduce velocity by reducing pressures however some say that the pressure reducing ability means you can load a considerable amount more powder into the case.

What are your experiences and findings with coatings? How are they best applied to bullets? What do they accomplish, what are they good for? Which one is best? Specifically want to know about hex boron nitride.
 
I know David Tubb swears by it.

I don't coat bullets myself, but if I were going to HBN is the material I would choose based on the lack of sulfur making it chemically inert compared to WS2 or Moly S2.

According to all sources, standard application techniques work just fine.

Jimro
 
I used 115 DTAC bullets that were BN coated, and I'm thinking I read he coats them to help put that first cold bore round into same group as the rest of his shot string when firing for score.
They shot nicely in the rifle I used them in.
 
Hey thanks for the feedback. That's really interesting to me about making the cold bore shot the same as those following it. Because with many hunting rifles me and my friends observe a pattern where you get all bullet holes touching or pretty close and then there's always one off and away from the rest (not by much but enough to frustrate). That's the cold bore shot, I've come to realize.
 
I would expect the HBN coating to slow the rate of fouling accumulation, as moly does. But a lot of rifles throw a first shot out because the barrel is cold and the action is not trued and so thermal expansion creates stress that is asymmetric around the bore axis, actually moving the muzzle slightly and changing the force applied by recoil to the apropos recoil moment. So I would say that unless your receiver is blueprinted and the barrel floated, you can't count on the bullet coating addressing the problem. It may or may not.
 
Even with a blueprinted action and true barrel you can still get "fouling walk" that puts a Clean Cold Bore (CCB) shot outside the rest of the group as copper and powder fouling change the coefficient of friction between the bullet and barrel over subsequent shots.

I knew a police marksmen who would meticulously clean the rifle after at training session only to fire 3 rounds before the rifle goes back into the arms room so that the next round down the pipe will be in the group, and not an out of group CCB shot. With a stainless steel Rem 5R barrel, he wasn't too worried about corrosion in the arms locker.

So if your rifle does this (and not all rifles do) then maybe coating bullets will put the CCB into the group. I don't know though, all the other snipers I knew just put their CCB corrections into their dope book since it is generally repeatable from every clean cold bore.

Jimro
 
I think we were saying the same thing, just coming at it from opposite directions. A blueprinted rifle still needs fouling shots with loads that foul normally. A rifle that fouls less due to bullet coating can still heat walk if it isn't blueprinted. If you both blueprint and coat the bullets, then you maximize the likelihood of seeing less clean/cold shot differentiation. Still no guarantee there won't be any, though. Choice of powder and how much and how fast it lays down fouling can also affect it, so a clean powder, like Vihtavuori, may be important to help things along.
 
Yeah, I was trying to add to what you wrote, not imply you were wrong.

In the quest for repeatable accuracy any sort of bullet coating is the absolute last step I'd take, as at that point the gains are really beyond my ability as a shooter from a sling. From a rest I might see it, but the only game I know where it could be really helpful is F/TR class (aka belly benchrest).

Jimro
 
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