Hexagonal Boron Nitride is another bullet coating similar to moly coating and different than moly. I tossed around the idea of coating subsonic wedge bullets with Hbn to test it out.
I am sticking with the IMR4227 subsonic load at 10.2 grains with the 180 grain wedge flat point stuffed on top . I tumbled the bullets with .177 copper BB's pre-coated with Hbn, this rotary tumbler is then charged with more Hbn and some 180 wedges then let it tumble for 3 hours to impact coat the wedgies. I used the search link to source out some older tests with Hbn by other 300BlkTalk members so I am not concerned with SD numbers resulting from the coating. My first goal is to check the first round flyer eliminating issue David Tubb claims....and better consistency! All testing will be at 100 yards.
Top bullet naked, bottom bullet Hbn coated.
One ragged hole! The quest for accuracy continues...
Bob the nailer
NRA Life member
Varmint Hunters Assoc. Member
American Gunsmith Association
www.knowyourzero.com
I looked into tungsten at one time, never got past the curios stage. Will be interested in what you find.
The military did a few studies and HBN seemed to show promise. No real conclusions could be drawn outside a margin of error, but it was military loads.
Interesting read dellet, I also found it necessary to fire several coated bulets to coat/condition the bore before things setteled down. I have only tested 20 rounds so far and need to load another run of 50 for testing, just takes some time to build loads as perfect as I can to narrow down the error factor to the nut behind the trigger
One ragged hole! The quest for accuracy continues...
Bob the nailer
NRA Life member
Varmint Hunters Assoc. Member
American Gunsmith Association
www.knowyourzero.com
One of the people I talked to was a firm believer in tungsten. There was a question as to whether it was the tungsten or bullet weight that was made his results so impressive. It was a 300 grain bullet, designed for Blackout subsonic. Shot very well, very far, didn't stop for much.
It was his feeling that once the barrel was coated, the benefits remained with jacketed, but it was difficult to document.
Local company. 308 subs with a 175 SMK, tungsten coated.
Found an article on Speer 150 grn Gold Dots and was suprised to see they are coating them in Hbn. I have been getting good results with the coating on subsonic Wedge bullets. Ok so I did change a few things to the load, I am still sure the Wedge bullets are a deal for .09 cents a pill and started to rework my data with a 1-7 twist sub dedicated ar. I started thinking if Hbn reduces friction and slows velocity some a greater powder charge will bring it back up, now I still have empty case space with the Wedge style bullet and I want a cleaner burning powder that will not blow back unburnt powder thru the gas system. Reading old threads on other members Wedge data I came across N120 as a good clean burning choice so with a range of 9.3grn - 10.3grn I have been fine tuning the load while filling the empty case space with Puff-Lon ballistic filler ( this will also increase velicity some due to filling the empty void ). It's been way to cold to run a chrno to record actual velocity however no supersonic crack is noticable "unsupressed" so lets call it a reduced load. Final loads are ready for ladder testing to find the sweet spot and with WMA converted brass, accuracy looks really good.
One ragged hole! The quest for accuracy continues...
Bob the nailer
NRA Life member
Varmint Hunters Assoc. Member
American Gunsmith Association
www.knowyourzero.com
Update on Hbn/Puff-lon testing. Working with a charge weight of 10.5 - 10.7grn of N120 topped off with Puff-lon and also testing naked bullets with Puff-Lon and with out Puff-Lon. What I have learned so far is coated bullets with Puff-Lon reduce wild flyers with the Wedge 180 grn bullet, 50yard results with coated/Puff-Lon loads yeald a 1" higher POI as compaired with naked wedges and wedges with out Puff-Lon. Still playing with seating depth around the 2.120" - 2.123" I found shorter and longer C.O.L. than this don't work well with my 1-7 AR, still no chryno data with these polar vortex storms that only give me a small window of semi calm shooting hours. I'll get there with the accurate loads right now it's finding time weather permiting.
One ragged hole! The quest for accuracy continues...
Bob the nailer
NRA Life member
Varmint Hunters Assoc. Member
American Gunsmith Association
www.knowyourzero.com
. I tumbled the bullets with .177 copper BB's pre-coated with Hbn, this rotary tumbler is then charged with more Hbn and some 180 wedges then let it tumble for 3 hours to impact coat the wedgies. I used the search link to source out some older tests with Hbn by other 300BlkTalk members so I am not concerned with SD numbers resulting from the coating. My first goal is to check the first round flyer eliminating issue David Tubb claims....and better consistency! All testing will be at 100 yards.
I must say 300 Blk is the most Intriguing cartridge I have loaded for yet.