Hexagonal Boron Nitride and the SMK 175

[zfk55]

We're about to begin a process on Sierra M/K 175 projectiles, and we're going to use Hexagonal Boron Nitride. After a number of correspondences with the maker of the rifle, he's agreed that HBN is superior to Moly in that HBN doesn't have the eventual adverse effects on the bore inherent in Moly coatings.
This rifle <span style="font-style: italic">must</span> use a coated projectile to gain the warrantee of moa/1,000 yards from the maker as it is specifically designed to function in that manner.
The rifle is a dedicated SMK 175 build in that the chamber and throat are specifically reamed for that projectile profile and no other. We're avid Berger VLD users, but they won't work with this particular rifle.
We have a Thumlers Tumbler and a source for BHN, and the process seems to be a simple one but its also something in 45 years of reloading I've not yet done, thus my enquiry.
Has anyone here performed a similar process with Moly, or better yet, with HBN specifically? Any inside info would be greatly appreciated.
Thanks you

zfk55

 

[bfoosh006]

Re: Hexagonal Boron Nitride and the SMK 175

I haven't tried it...but, look here... http://6mmbr.websitetoolbox.com/search?searchid=2480791 let us know how it works out.

 

[427Cobra]

Re: Hexagonal Boron Nitride and the SMK 175

I use it and like it alot, I use peanut butter jars(plastic) about half full of steel BB's, 20 grains of HbN, and 100 155 scenars, I put them all together and throw the jar in my RCBS tumbler with about 1/3 the crushed walnut media for about a hour, scenars have a very thick copper jacket, 175SMK/178Amax about 30 minutes, I remove the jar and dump the BB's and bullets in a metal steaming pan from Walmart, the BB's fall into the lower pan and the coated bullets remain, if the bullets look like powdered donuts, too much HbN, and lastly I dust off any remaining HbN with a old USGI wool sock. It should take a little more powder to achieve the same FPS, as with any coating, but the none of the negatives of Moly or Danzac are there with HbN, no buildup, no conditioning, no trapping of water, and the ease of cleaning will amaze you.

 

[zfk55]

Re: Hexagonal Boron Nitride and the SMK 175

Thank you very much. We're ordering hBN monday mornnig. Its tough having a rifle like this without anything to feed it. There were 10 rounds of moly coated put through it by the maker to zero it. The target came with it. Ten rounds, one nickel sized hole.
I'll post target pictures once we get things up and running.
Thanks again.


zfk55

 

[427Cobra]

Re: Hexagonal Boron Nitride and the SMK 175

1 pound should do about 350000 bullets, .5 micron!