Or perhaps I'm assuming too much: Can anyone confirm that properly hBN-coated bullets show reduced muzzle velocity vs uncoated bullets, holding all else constant (load and bore)?
Trouble with hBN bullet coating
- Thread starter David Bookstaber
- Start date
GSPV
A failure to plan is a plan for failure.
I use HBN in a Lyman moly coating unit It's vibratory and uses ceramic media.
To the people that asked:
1. The bullets have to be clean and totally free of any kind of oil or grease. Even body oil on them from handling will cause problems
2. It helps for the bullets and media to be hot. I get mine hot in the oven. This is something that I picked up from a German Salazar article.
3. I clean my bullets thoroughly with Dawn, rinse, then rinse in acetone and dry.
4. After coating, I polish mine in the corn cob media that comes with the unit. Works great.
5. I used to polish the coated bullets with an old sock. When I used that process, the chronograph showed a small velocity loss. Since changing to polishing in the unit with corn cob media, it no longer shows velocity loss. YMMV
Try cleaning up some bullets that you've worked well with in the past and see if your process works on them again. If so, it's something with the bullets. If not, it's something about the process.
To the people that asked:
1. The bullets have to be clean and totally free of any kind of oil or grease. Even body oil on them from handling will cause problems
2. It helps for the bullets and media to be hot. I get mine hot in the oven. This is something that I picked up from a German Salazar article.
3. I clean my bullets thoroughly with Dawn, rinse, then rinse in acetone and dry.
4. After coating, I polish mine in the corn cob media that comes with the unit. Works great.
5. I used to polish the coated bullets with an old sock. When I used that process, the chronograph showed a small velocity loss. Since changing to polishing in the unit with corn cob media, it no longer shows velocity loss. YMMV
Try cleaning up some bullets that you've worked well with in the past and see if your process works on them again. If so, it's something with the bullets. If not, it's something about the process.
GSPV, thanks -- excellent info.
How hot do you preheat the bullets and media?
Do you vibrate directly in the Lyman bowl, or do you put media and bullets in subcontainers?
If the bullets show no velocity loss are you simply getting reduced fouling? Or any other measurable benefits?
How hot do you preheat the bullets and media?
Do you vibrate directly in the Lyman bowl, or do you put media and bullets in subcontainers?
If the bullets show no velocity loss are you simply getting reduced fouling? Or any other measurable benefits?
I have had really good results with similar methods to what GSPV described.
I used to use the Tubb method of bullets, HBN and no media in his bottle, rolling around in my vibratory bowl all by it's self. It rolled around similar to the vid above but also circles the bowl too. I found that I had to put in a lot of bullets and a little bit of HBN for the best results. When we tried to do just a few bullets it beat(scratched) up the bullets. I have since switched to the steel shot in my same Tubb bottle in my vibratory bowl. I like the shot a lot. It makes the finish a bunch more consistent. I'd like to try the ceramic some day.
I did some testing with a rotary tumbler, but I must have messed up because I did not get the results I do with the vibratory....so I'll keep on doing what works for me. I have no doubt that the rotary tumblers work...too many well respected guys doing it successfully.
I like to wash my bullets with a quick hit of brake clean and roll them in a rag till dry. I then put them in a shallow pan and apply heat with a propane torch till they are just a almost too hot to handle(guess 130) I dump them into the Tubb bottle with about a 1/4 full of steel shot. I can run 200 6mm bullets and still have about an inch of room under the lid. I found that if I put a wrap of duct tape around the rolled ends of the bottle it rolls over and over a lot faster. I have since found another (vitamin) bottle the same size as the Tubb, so I can coat two bottles full at a time. They chase each other around the tumbler like a couple of stock cars. After about two hours they come out satin HBN.
I found that if I use too much HBN it clumps and never really coats and is easily rubbed off with a rag. Good luck, you'll find the bug. It may be best to just start over with all clean stuff.
I used to use the Tubb method of bullets, HBN and no media in his bottle, rolling around in my vibratory bowl all by it's self. It rolled around similar to the vid above but also circles the bowl too. I found that I had to put in a lot of bullets and a little bit of HBN for the best results. When we tried to do just a few bullets it beat(scratched) up the bullets. I have since switched to the steel shot in my same Tubb bottle in my vibratory bowl. I like the shot a lot. It makes the finish a bunch more consistent. I'd like to try the ceramic some day.
I did some testing with a rotary tumbler, but I must have messed up because I did not get the results I do with the vibratory....so I'll keep on doing what works for me. I have no doubt that the rotary tumblers work...too many well respected guys doing it successfully.
I like to wash my bullets with a quick hit of brake clean and roll them in a rag till dry. I then put them in a shallow pan and apply heat with a propane torch till they are just a almost too hot to handle(guess 130) I dump them into the Tubb bottle with about a 1/4 full of steel shot. I can run 200 6mm bullets and still have about an inch of room under the lid. I found that if I put a wrap of duct tape around the rolled ends of the bottle it rolls over and over a lot faster. I have since found another (vitamin) bottle the same size as the Tubb, so I can coat two bottles full at a time. They chase each other around the tumbler like a couple of stock cars. After about two hours they come out satin HBN.
I found that if I use too much HBN it clumps and never really coats and is easily rubbed off with a rag. Good luck, you'll find the bug. It may be best to just start over with all clean stuff.
GSPV
A failure to plan is a plan for failure.
dbooksta said:
I put everything in the oven on 175. That's as low as my oven will go. Seems to work.
I do it directly in the Lyman bowl. Maybe the sub containers would be better. I don't know. This works for me and I'll have to stick with it.
All I have ever expected from the HBN is to make it through 24 or 25 (depending on format) record shots in a yardage plus foulers and ease of cleaning when I do. Frankly, I have no proof that it does. Just going on what my mentors have told me.
I have coated projectiles with moly and hbn by both methods, impact and tumbling , impact using BB's or bearing balls is significantly quicker , about an hour for do 200 155.5 Bergers which have not been cleaned or heated.
Sierra 155's need a good wash , I use " TruckWash '' detergent , thats it no heating no nothing , if you are going to vibrate , small containers seem to work best and pre plate the BB'S first , give them a good rattle by themselves with about 1 grain of moly or hbn. A 22 rimfire spent case will measure out about .9 grain.
Tumbling takes takes about 2-3 hours in my home made machine pictured below,which I am now forced to use since the vibrator broke.
Also you will see 155 Sierras 2156 hbn coated and 155.5 Bergers mollied both done in the tumbler.
Mike.
Sierra 155's need a good wash , I use " TruckWash '' detergent , thats it no heating no nothing , if you are going to vibrate , small containers seem to work best and pre plate the BB'S first , give them a good rattle by themselves with about 1 grain of moly or hbn. A 22 rimfire spent case will measure out about .9 grain.
Tumbling takes takes about 2-3 hours in my home made machine pictured below,which I am now forced to use since the vibrator broke.
Also you will see 155 Sierras 2156 hbn coated and 155.5 Bergers mollied both done in the tumbler.
Mike.
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