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> hBN Bullet Coating
hBN Bullet Coating
@ 06:57 pm (GMT) |
Mark BarrettI recently started experiments with hBNcoated bullets in 7mm and 30 cal. I noticed that the force required to seat the bullets was excessive if not extreme compared to loading the same bullets uncoated. Additionally, pulling bullets with a collet die was extremely difficult because the hBN made the collet too slippery to get a grip on the bullet. When I was successfully in pulling bullets they had grooves jacket that does not occur without Hbn. I did no get significantly less copper fouling in these tight muzzle rifles though minor improvement was there. I was able to ease seating pressure by roughly 70% by coating the bullets with Hornady One Shot case lube. The hBN I'm using is uMicroLubrol 0.5um 98% or greater purity. I did get roughly 30fps extreme spread and think I will continue to experiment. Is anyone else is seeing the same problems or have tips on using hBN properly? |
Replies
@ 11:33 pm (GMT) |
Nathan FosterRe: hBN Bullet CoatingHi Mark, it sounds as though the neck tension of the brass is too tight for this application. This could also cause some scraping and result in an uneven coating.Yours is not an isolated problem. One shooter will state that all is well while another will state the same complaints as yourself. The problem is as a result of the initial coating process which can lay down some large particles. These particles become crushed during ignition and bore engagement but are harder to break down by hand during seating. To really make the most of some of these coatings, it can be helpful if you can flare the case mouth ever so slightly. However, the flaring has to be quite exact. Too much flare and the case will jam in the chamber while at the same time affecting neck tension. A small flare will in contrast 'disappear' as the bullet is seated. A flare is also important when fire lapping. But- I believe your first port of call may be to alter neck tension via your FL / Neck die. If you have not already done so, try a Lee collet neck die which will allow you to reduce neck tension. Neck flare dies used to be common but they are not popular any more. You can in a pinch use a .30 cal Hornady stem button to flare 7mm cases and a .338 button to flare .30 cal- but you must be careful as to how this case working affects concentricity. This next is I believe off topic as far as your issues are concerned: If the bore is still producing heavy copper fouling after coating, there may be other factors at play. The chamber may be rough, the bore itself may be rough. Sometimes it can be simply as a result of very tight bore dimensions. What we have to work out first, is whether the copper fouling is helpful or whether it is a hindrance. In many rifles, a measure of copper fouling can be useful and as I wrote in the books, it can actually help accuracy and can have a positive effect on BC- something few people talk about. But then there are situations where a bore fouls too heavily. A hunting rifle that becomes gloopy and inaccurate after a dozen shots can be a major problem. A comp rifle that doesn't make it through the day is a problem. In some instances, the only way forwards with a heavy fouler, is to do our best to hand or fire lap the bore with bullet coatings as a further solution but not as a sole solution. Bullet coatings are not an instant fix for all ills. Furthermore, in a bore that already produces very low copper fouling, bullet coatings can hinder accuracy (as per reasons outlined in Accurizing book / bore finish versus bore dimensions). All we can do is experiment. Another example of friction: Cases have been chamfered but edge is still sharp. You try to seat a bullet but resistance is firm with risk of loss of concentricty during bullet seating. Remedy: simply spin a projectile in the case mouth before seating. The spin puts a microscopic layer of copper on the case mouth burr and acts as a lube. |
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@ 03:09 am (GMT) |
Mark BarrettRe: hBN Bullet CoatingNathan,Thanks for such a detailed comments. I buying your excellent books, and subsequently 3 sets of Lee collet neck sizing dies, factory crimp dies for my favorite rifles, Sinclair and Hornady concentricity gauges I'm well prepared to experiment. I do have some old neck flaring dies from cast bullet rifle loading I will try if needed. The tip on spinning the bullet is one I've never heard before but certainly appreciated! These three rifles foul pretty heavy after 25 or more rounds. Two shoot excellent from first shot to around 30 rounds. I usually clean after that and not sure what high round count accuracy looks like. The Scotch Bright maroon pads delaminated cuts time by 50% or more so I'm not complaining. I will get the 300wby m700 classic back to accuracy one way or another as there is too much history to sell her and the factory wood stock looks like tiger eye after 20 coats of tung oil and pillar and epoxy bedding job I did 10 years ago. But I digress. I searched for 5 months on blogs and never found the hBN question satisfactorily answered l, so I thought I would bring it up in this forum where I have learned so much already. Thanks again! |
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@ 02:45 am (GMT) |
Mark BarrettRe: hBN Bullet CoatingIt has been quite a while since I ran new hBN experiments. I did use the lee Collet dies for my 7mm-08 and new Sendero 300 Win Mag as per Nathans recommendation above.The 7MM-08 is shooting about 0.5MOA or perhaps a bit better. The 300 win Mag is shooting about 0.5-0.9MOA, but working on loads. The 7mm-08 is shooting 162gr ELD M at 2650. The 208gr ELD-Ms at 2950 in the 300 are beating me up even in the Sendero, but I heal after a couple weeks. velocities were measured with a Labradar Doppler radar. I love that Labradar BTW. It is worth the $559 USD. I did the break in as per Nathans Accurizing Bolt Action Rifles book on both rifles, so I don't know if the results are due to the break in or the hBN, but I suspect both. I tried to post pictures of of before and after cleaning muzzles the rifles, but was unable to. I will try to figure this out in the future. The bottom line is that these rifles are fairly accurate and don't hardly foul at all and SO much easier to clean. Note I used the white Scotchbrite poly pads wrapped spiraled down a bronze brush with Sweets 7.72 copper solvent to do a quick clean as I will be back at the range soon. So what was formerly a 2 hour job (or possibly longer?) it is a quick half hour or less job now. I will experiment without hBN after deer season to see if that really was what caused the improvement. Deer season is a month and a half away and I have to build my skill set as much as I can for longer range shots, but I'm feeling it will be very dangerous for a Arizona Coues deer to be withing 600 yards now with either of these rifles under the right circumstances, possibly a bit further. Best, Mark |
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@ 11:02 pm (GMT) |
Mark BarrettRe: hBN Bullet CoatingForgot to mention that the bullets seated very easy in the cases. The ES on the small sample size of 2 shots on each rifle using radar chronograph were 1 and 2 fps. These were probably not crimped very heavy with the Lee crimping tool. I hope all are not bored to tears with this, but it is interesting to the experimenter... |
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@ 09:02 pm (GMT) |
Nathan FosterRe: hBN Bullet CoatingThanks for the follow up Mark, its good to follow your progress.Will be interesting to see if you can sneak those .300 loads down a bit and how future experiments go. But its also good to stop for a bit, set your max range and just go hunting. Of the new range of Hornady bullets, the new 208gr is a wee bit finicky. The MAX OAL, at least for this current batch I have, is roughly 20 thou longer than the A-MAX, even though they appear the same at first glance. This bullet needs some jump experimentation. Everything else I have tested so far seems to be fairly straight forwards apart from this single bullet. |
@ 06:42 am (GMT) |
jasonRe: hBN Bullet CoatingNathan, I seemed to have created an issue for myself. For some reason its become more apparent lately.My nice ultrasonic cleaned brass is too clean. Hard seating. Iv added graphite to the inside neck before seating, which helps a lot. Is there any negative effects of doing this? I'm starting to graphite necks for sizing and remove redding sizing wax off the body with a rag instead of cleaning ultrasonic. Sizing is harder than using the redding stuff in the neck, but am trying to not have to swab the neck clean, or does it not really matter. (Leave the lube in there?) |
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@ 08:05 pm (GMT) |
Nathan FosterRe: hBN Bullet CoatingHi Jason, there are no issues with leaving graphite in the case neck other than changes in pressure / sweet spots. I have also deliberately coated bores and also bullets with no ill effects during experiments. |
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@ 09:22 pm (GMT) |
jasonRe: hBN Bullet CoatingThanks Nathan, good to hear. As there shooting well at this stage.I even put a little graphite in the primer pocket to help with seating primers. |
@ 03:40 pm (GMT) |
Bryan WebsterRe: hBN Bullet CoatingQuote: Thanks Nathan, good to hear. As there shooting well at this stage.
I even put a little graphite in the primer pocket to help with seating primers. I would never put anything in the primer pocket but a primer Jason. |
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@ 04:54 am (GMT) |
jasonRe: hBN Bullet CoatingQuote: Quote: Thanks Nathan, good to hear. As there shooting well at this stage.
I even put a little graphite in the primer pocket to help with seating primers. I would never put anything in the primer pocket but a primer Jason. Bryan, I wondered about doing it too. But so far no bad effects. Do you have a reason why I shouldn't? I'm open to thoughts on this... |
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@ 07:42 pm (GMT) |
Bryan WebsterRe: hBN Bullet CoatingNo need for one, and seating the primer firmly in the bottom of the recess is paramount in ensured accuracy and reliability let along fouling the primer and possibly getting misfires. |
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@ 07:04 am (GMT) |
jasonRe: hBN Bullet CoatingNo need for one...OK, I get your not into it, But that sounds like my dads favourite reply.... Because I said so. I'm into some kind of theory or experience behind the statement. I feel seating and feel of seating is better than the situation I had before. Yes I probably should really address the issue instead of finding a fix for it, Which I have now. I cant say its a good thing to do, but I tried it and so far, so good. As far as fouling the primer, maybe. But you can hardly see any graphite in there, any less and there would be none.its just a wipe with a cotton bud. I certainly wouldnt try any wet lube. Iv also concentrated on the sides of the primer pocket, not the bottom. I did think maybe the primer would act different backing out of the pocket while firing, I guess its no different to a loose primer pocket. Oh well thanks for giving me things to think about as to what might happen. |
@ 12:40 am (GMT) |
Paul LevermanRe: hBN Bullet CoatingJason - just some thoughts on the graphite issue. It is a dry lube, so it may make the primer act loose, but if your primer pocket is that loose that there is enough of a gap to be lubricating the primer , you probably shouldn't be using that case anyway. Not really sure if contamination is a problem, that would depend on how much you use. When I neck size, I use dry graphite as a lube, the case neck dipped into it. There is always some left on the neck, even after wiping it off, yet the case always seems to grip the chamber walls. Might be apples and oranges here, but brass to steel and steel to brass, should act the same. And if it does make the primer more slippery, then maybe those goofy Lee Loader primer pins won't keep sliding out of the die. |
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@ 06:43 am (GMT) |
jasonRe: hBN Bullet CoatingPaul.The primer pockets arnt actually loose. I just figure they may act like it with graphite, Therefore back out more easily. Its my understanding that they back out when fired, hit the bolt face and get pushed back in anyway. It may just happen more easy. I know the real answer is I shouldn't need to graphite them. How it started is my ultrasonic cleaner gets the necks, well the whole case too clean and seating projectiles is hard and un-uniform. Iv noticed others have the same problem and some say graphite will help, others say you can use steel wool. I thought I'd use steel wool first. And it worked well just before seating the bullet. Next time I did the same, but I used the steel wool maybe a day or two before seating the bullet. I figure if the whole case was too clean so would the primer pocket be. However doing it ahead of time made it even worse. I had a primer stuck half in a case, using the Lee hand held priming tool this ment I couldn't remove the shell holder either. So more out of desperation and not wanting to stop my loading that's when I used the graphite, in the pocket too. So far it has worked well. But yes the real answer should be, don't clean so much, or the way iv now headed, not ultrasonic clean at all. Just brush the neck and use a rag to remove the lube from the outside of the case. A keep it simple approach. Too clever for my own good. Haha. But yes, other than the unknown effects seating and feel of the neck and primer was really good. |
@ 08:58 am (GMT) |
mark whiteleyRe: hBN Bullet CoatingHi JasonI don't have anything to offer about hBN coatings but I do about the squeaky clean you get from an ultra sonic cleaner, tumble the cleaned brass in your typical case polisher after ultra sonic cleaning as it puts a slip feel back on the case, ultra sonic cleans, cases polisher polishes also if your brass goes a salmon colour after ultra sonic cleaning it has been in to long and is taking the zinc out of the brass damaging it, solution is stainless steel media wet tumbler 
hope this helps |
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@ 01:58 am (GMT) |
Mark BarrettRe: hBN Bullet CoatingNathan,Great to know about the new 308 208gr ELD-M. I'm seating max magazine length in the Sendero and the grouping is coming back into .5 MOA at 80gr Retumbo for 2950fps. More work needed. I'm not hunting with it. Thanks for the help and good advice on picking a range. My old game warden friend Kimrod (Kim) Murphy passed away and his favorite hunting quote was: "The best sportsman and hunter is the man who finds the most game, kills the least, and leaves behind him no wounded animals" - Joe V. Proshaska State Game Warden 1917. With that reminder I will try to live up to his expectations. He may have let me go on a citation, or two... Thanks again, Nathan. Mark |
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@ 06:24 am (GMT) |
jasonRe: hBN Bullet CoatingThanks mark. That is helpful.I might try that. I take it you use some kind of polish with corn or walnut media, what's your brew? |
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@ 10:26 am (GMT) |
mark whiteleyRe: hBN Bullet CoatingQuote: Thanks mark. That is helpful.
I might try that. I take it you use some kind of polish with corn or walnut media, what's your brew? the cases in the photo are cleaned in a rebel 17 wet tumbler and that's how they come out cleaned inside and out primer pockets as well with no detriment to the case. I must say I only ever clean my cases after initial prep (neck turn/anneal ect..) I like a bit of carbon on the inside of the neck I played with ultra sonic cleaners and found they do what they say they will by cleaning all the oils, carbon ect.. off the cases so they are a squeeky clean that does change neck tension, what I found to help was to tumble the cases after ultra sonic cleaning to polish them and give the slip feel back, I do know people who dip there case necks into graphite before seating the projectile after cleaning cases and apparently it helps with there extreme spreads but I cant say as I have not tried it. regards mark |
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