HBN coated bullets
- Thread starter blaster50
- Start date
I coat my bullets with danzac for one reason, to reduce copper fouling to extend accurate shot strings. It is very effective at this. I use it on all calibers, even my hunting rifles. There is little or no velocity loss and the only reason I would expect it to affect barrel life is due to less frequent and easier cleaning. Obviously, I feel it is worth the small extra effort. I've won multiple registered benchrest matches with 300-400 rounds on the barrel between cleaning.
I realize that the op was about HBN specifically, but the point remains the same IMO.
I realize that the op was about HBN specifically, but the point remains the same IMO.
The claims of velocity drop and cleaning ease have validity in my experience. Subsequent shots after a cold bore shot are closer with coated bullets but not the same.
How much velocity loss are you seeing and what are you shooting? IME using Danzac coated bullets in typical BR cartridges, it's always been about 50 fps or less...usually less. I agree with you about cleaning ease and poi change being less from clean, cold bore to next shots. Usually only takes a shot or two for the barrel to settle right in.
Same here only with HBN
Joe R
Gold $$ Contributor
It is very close at 100 and 300 yards after that I can't say for sure. Here's a cold bore shot at 100 and 300 yards. Guess which one is the cold bore shot?
A friend HBN his bullets for his 220 Swift and he also noted a velocity drop using a magneto speed and averaged across 10 shots. From his research this is due to less friction between the bullet and barrel. So he started to increase the powder charge to bring it back to his original speed ended up being 0.8gr more.
He also has found that cleaning easier especially less copper and longer shot strings before accuracy starts to go. Barrel life hmm I'm still on the fence especially regarding the throat area and the start of the rifling. As I did find a paper on the net regarding this area and it did mention high heat and pressure your essentially creating a plasma and thus slowing plasma cutting the rifling away.
He also has found that cleaning easier especially less copper and longer shot strings before accuracy starts to go. Barrel life hmm I'm still on the fence especially regarding the throat area and the start of the rifling. As I did find a paper on the net regarding this area and it did mention high heat and pressure your essentially creating a plasma and thus slowing plasma cutting the rifling away.
I've coated many thousands of bullets for many calibers and cartridges and have not seen that much change but I suppose it is possible. In fact, I've tested and shot the same loads in many cases, with both naked and coated bullets, with little to know difference in accuracy. I'd say that amount is rather exceptional, but I won't doubt you or your friend.
Nevertheless, the only reason for a loss of velocity is lower pressure due to less friction. As long as there's room, just add more powder, if velocity is what you're after. I've never been one to chase speed. I only care that it shoots small and fouls less.
I think what you have shown here is quite typical from a good barrel. I see about the same difference with my 1st shot to the rest. Others may see slightly more but again, I think your pic is quite representative of what to expect.
ImBIllT
Silver $$ Contributor
My experience with Danzac has been an increase in velocity after increasing powder charge. A charge that was leaving primers flat with naked bullets would leave them round with Danzac, and after loading up to primers that are beginning to show flat edges, the velocity was increased beyond the original load. Guns that shot well clean, would shoot well for many more shots before accuracy dropped off, and guns that shot well dirty would shoot better clean with Danzac than with naked bullets. Danzac and HBN both claim to avoid the molly ring of death. I will go a few hundred rounds between a wet patch followed by some dry patches, and up around 1000 before brushing. HBN was touted as being better than Danzac, so I'd say it's worth trying. If you don't bump the load up, then yes, you'll have velocity loss. I don't shoot naked anymore, so I just work a load and call it good. No need to compare it to naked bullets anymore.
First and foremost the first cold bore shot is on elevation. I shoot three times a week and Ive never had a climbing cold bore shot string- ever.
Second, although you see a drop in velocity during load development, this allows you to increase the load to achieve node velocities that would not be attainable with naked projectiles. I use one of those fantastic Bartlein 5R barrels (originally a 35 inch blank becoming a 28 inch finished after slugging for a constriction) chambered by LRP Solutions. Projectiles are Optimus .308 HBC 155.5 gr pointed with a Hoover System and HBN coated. My node velocity is 3185 fps with no signs of pressure.
Third, barrel life. My last competition barrel did 12070 rounds. It stopped performing past 11800 rounds. My record score of 200.19x at 300 meters (2 inch x ring and 4 inch 10 ring) (shooting sling and irons)happened around that time.
Fourth, cleaning: not sure. I clean after every shooting day. I use HBN for accuracy purposes only.
Second, although you see a drop in velocity during load development, this allows you to increase the load to achieve node velocities that would not be attainable with naked projectiles. I use one of those fantastic Bartlein 5R barrels (originally a 35 inch blank becoming a 28 inch finished after slugging for a constriction) chambered by LRP Solutions. Projectiles are Optimus .308 HBC 155.5 gr pointed with a Hoover System and HBN coated. My node velocity is 3185 fps with no signs of pressure.
Third, barrel life. My last competition barrel did 12070 rounds. It stopped performing past 11800 rounds. My record score of 200.19x at 300 meters (2 inch x ring and 4 inch 10 ring) (shooting sling and irons)happened around that time.
Fourth, cleaning: not sure. I clean after every shooting day. I use HBN for accuracy purposes only.
Generally with moly and HBN (have no experience with Danzac) you will see a little "drop" in preasure for the same speed with the coates bullets that you had with naked bullets so like you said once you get to the same preasure level as before with naked bullets you should have gained some speed
Mike. I've only saw a velocity drop of between 7-15 fps between HBN or Danzac vs naked bullets. I use my 35P for every test session.
That's about what I've seen and expect. So basically, nothing. I said 50fps or less...usually less..in my prior post. I would consider 50fps to be about the most you might see, with long bullets and a lot of bearing surface. Not what we typically shoot. I think your numbers are pretty spot on. You and I may have discussed this at some time or another.
Mike. I don't know if you ever read that article that was put out by the United States Air Force. They conducted a test that used HBN, Danzac and moly coated bullets. Interesting reading.
I don't recall reading it. Have a link?
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