Re: hBN as a neck lube?
This thread started with a discussion on whether or not lube affected chamber pressure and case stretching. Information was provided that says lube can be a problem when used excessively.
However, with respect to reduction in friction, both Boron Nitride and grease do the same thing; they reduce it. The first question to ask is, "Is the bolt thrust increased by the use of Boron Nitride"? The second question is, "If so, how much is the increase and does it present a risk"?
In this case, probably not; but how do you know it does not? As Casey stated, Boron Nitride is a lubricant of high lubricity for high friction applications. Would it be considered a better lubricant than the geases of 1920? If so, it should do as good or better at eliminating the friction between the case and the chamber wall.
Yes, it is good to keep your library updated. It appears that my current data says lube, under some circumstances, can be a problem and provides test data to support it. If you have any data on the use Boron Nitride on fired rounds, please share so we can all update our libraries and benefit from your updated information.
As I stated in my earlier post, "This sounds like the extreme use of lube, but it appears that any lube will eliminate some of the designed friction between the case and the chamber. How much is too much is the question. The indications are clear that the presence of lube on a case does not increase the safety factor." Again, I think we are talking extremes of use whether it is grease or Boron Nitride. The question remains, "When do we reach that extreme"? To each his own opinion.