Bullet Coatings

[Popsbengo]

I'm curious to try coated bullets.  I know of two principle materials:  HBN and Molybdenum.  I prefer HBN as I don't want moly related metallurgical issues.  I understand that the reduced friction will decrease Mv as peak pressures are reduced.

While it's possible to increase load to recover lost Mv there are two things that puzzle me

1) Is it beneficial to either increase neck tension or jam the bullet to achieve consistent SD/ES (due to the lubricated neck releasing quicker)

2) Does the increased load (all be it recovered pressure remains the same) alter the harmonic node ? ie is it necessary to redo optimum charge weight tests?

Anyone out there got any real world experience?

[DaveT]

I have used Hbn in 260 Rem and 6mmSLR.

I did the load workup from scratch in the usual way so finding accuracy nodes was arrived at in the process.

I CAN say for certain that the bore stays waaaay cleaner and that I see no first shot fliers.

I am HOPING that bore wear....especially in the 6mm which I run 'hot' ..... will be much reduced but this harder to prove.

In terms of its application vs moly........ easy peasy and clean.

[Catch-22]

I too use HbN, both on bullets and swabbing in the bore, and think it’s very good stuff.

Calibre's used is 6.5x47 and my .338NM, but plan to coat .223 in the future too.

Whilst it’s ideal to start a new barrel with HbN from the start, if you’ve used naked bullets previously, just ensure the bore is spotless less clean (no copper) prior to shooting HbN because you want that ceramic coating to be applied to the barrel, not the copper.

Im unsure about neck tension as I’ve never compared before or after coating, but you could give it a try.

Generally HbN loads require at least a full grain, if not more, to duplicate naked loads. For the barrels I use HbN in, I can’t say if the harmonic node is different as I’d never developed a naked load in them and compared. But for previous rifles in same calibres, I find accuracy nodes are very similar. For example, a past Rifle in 6.5x47, shooting same powder (N140), primer (Murom KVB-223m) and bullet (123gn Lap Scenar), same dies (Whidden) had a very good node at 2940ps with low ES/SD. My new rifle with same components as above but HbN has its accuracy node around 2930fps.

With HbN I can push that load waaay higher, but I have no need to. I get zero pressure signs. The previous rifle with naked bullets was very close to the very upper limit.

I would say my cold bore shots, after cleaning the barrel after 2-300 rounds, are a lot more consistent. When cleaning, I strip everything out then re-swab the bore, I find I no longer need to foul the barrel like I had to.

The one thing I dislike about coating bullets is just the time it can take. I wash my bullets with hot water and fairy liquid. Once dry, put in the oven at 90-100degrees for 10-15mins, then into a screw top Tupperware canister with steel BBs and a screwdriver tip of HbN. Tumble for 4-5hrs. Then sift BBs from bullets. I try to do around 200 bullet batches, but it can be a little boring. 
Making a bore solution is easy. Small plastic bottle with 99% isopropyl alcohol and enough HbN so that it’s same consistency as whole milk. Before leaving for the range, I stick a patch that’s been dipped in the HbN slurry, down the bore a couple of times. The alcohol will evaporate within 30mins and will leave behind a white deposit of HbN. That coupled with the coated bullet will burnish the bore nicely.

[Popsbengo]

23 minutes ago, Catch-22 said:

I too use HbN, both on bullets and swabbing in the bore, and think it’s very good stuff.

Calibre's used is 6.5x47 and my .338NM, but plan to coat .223 in the future too.

Whilst it’s ideal to start a new barrel with HbN from the start, if you’ve used naked bullets previously, just ensure the bore is spotless less clean (no copper) prior to shooting HbN because you want that ceramic coating to be applied to the barrel, not the copper.

Im unsure about neck tension as I’ve never compared before or after coating, but you could give it a try.

Generally HbN loads require at least a full grain, if not more, to duplicate naked loads. For the barrels I use HbN in, I can’t say if the harmonic node is different as I’d never developed a naked load in them and compared. But for previous rifles in same calibres, I find accuracy nodes are very similar. For example, a past Rifle in 6.5x47, shooting same powder (N140), primer (Murom KVB-223m) and bullet (123gn Lap Scenar), same dies (Whidden) had a very good node at 2940ps with low ES/SD. My new rifle with same components as above but HbN has its accuracy node around 2930fps.

With HbN I can push that load waaay higher, but I have no need to. I get zero pressure signs. The previous rifle with naked bullets was very close to the very upper limit.

I would say my cold bore shots, after cleaning the barrel after 2-300 rounds, are a lot more consistent. When cleaning, I strip everything out then re-swab the bore, I find I no longer need to foul the barrel like I had to.

The one thing I dislike about coating bullets is just the time it can take. I wash my bullets with hot water and fairy liquid. Once dry, put in the oven at 90-100degrees for 10-15mins, then into a screw top Tupperware canister with steel BBs and a screwdriver tip of HbN. Tumble for 4-5hrs. Then sift BBs from bullets. I try to do around 200 bullet batches, but it can be a little boring. 
Making a bore solution is easy. Small plastic bottle with 99% isopropyl alcohol and enough HbN so that it’s same consistency as whole milk. Before leaving for the range, I stick a patch that’s been dipped in the HbN slurry, down the bore a couple of times. The alcohol will evaporate within 30mins and will leave behind a white deposit of HbN. That coupled with the coated bullet will burnish the bore nicely.

very interesting, not thought about swabbing out the barrel

Where do you buy your HbN ?

[Catch-22]

I bought from small retailers in the US because the UK stockists only do bulk industrial quantity. A small 1oz tub is probably enough to coat about 40,000-50,000 6.5mm bullets - a little goes a very long way. 

Note there are many different grades of HbN, with ultra fine 0.5U being the best for coating bullets (gets into the small pores of the jacket).
 

There’s actually a good retailer on eBay that I believe several here have bought from, including myself;

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F124111016193

[Catch-22]

Oh, one trick to know if you’re coating the bullets correctly is to see how much HbN residue is left in the tub after tumbling. If there’s surplus powder then you’ve put too much in.

I’ve also found that if you’ve used too much HbN, the bullets actually dont get an even coat and the bullets don’t feel particularly slippery. Lower the amount of HbN (as stated before - only the tip of a screwdriver is needed) and the bullets get a good deep coating.

When done right, give the bullets a gentle polish in a towel to remove excess (don’t worry - the pores of the jacket are impregnated with the HbN and it won’t wipe off completely) and the bullets take on a ‘frosted’ look and are slippery as hell.

Here’s a .338 Norma Magnum loaded with 300g Lapua Scenar coated with HbN - you can see the slight frosting but I can assure you the whole bullet is evenly coated is a very very slippery;

[fizzbangwhallop]

I bought some on Amazon back in April but haven’t got round to trying it yet, mainly as I didn’t have a clue as to how best to apply it...so many thanks to Catch-22 for the info above, very useful 👍

https://www.amazon.co.uk/gp/product/B07XZ45QZY/ref=ppx_yo_dt_b_asin_title_o05_s01?ie=UTF8&psc=1

They do another size tin as well. 

cheers

Fizz

[Catch-22]

You’re welcome 👍

I only got my info from reading around lots of various forums and a bit of trial and error.

I definitely think the most important things to bear in mind are;

1. Ensure bullets are clean prior to coating (no  fingerprint grease etc)

2. Heat the bullets up to help with impact plating

3. Don’t use too much HbN...use very little, less than you think

4. Don’t load too many bullets into your jar of BBs. In a 500ml plastic tub (I use a Tupperware screw top jar) I have about 250BBs and about 50 to 100 6.5mm bullets at any one time. Too many bullets in the jar and you’ll hinder the impact plating

5. Tumble the bullets for a good 3-4hrs then check. Bullets should have very little ‘clumpy’ residue - a nice thin even layer is what you want. If the bullets lack an even coating, stick them back in the tumbler for another hour.

6. Be very careful with the HbN. Nano particles are able to penetrate the skin. I use a screw top lid and then cover the join with gaffer tape to stop any leak when in the tumbler. Don’t inhale (best use a mask) when opening jar and sifting BBs from bullets.

7. Polish the newly coated bullets before seating - polishing makes them slippery as F!

8. You don’t need to strip clean the bore after every shoot. I simply push a patch through to get the carbon out. Patch 2 or 3 should be relatively clear. I don’t re-swab the bore before the next shoot - just go shoot. But I will do a deep clean after 300 rounds or so. Definitely re-swab the bore ahead of the next shoot.

[Tralle]

I gave up on the HBN, I really wanted it to work. 

Experiences exessive seating pressures, to the point of deforming bullets and seating stems. 

Annealed and FL sized brass. Normal bullets would seat easily.

Seated bullets was really hard to pull and they had some wild galling/scratches on them.  

Tried in a jar with and without BB's, tried a small vibro tumbler filled with BB's.  Both gave similar results. 

HBN was from a German source, boroshots if i remember correct. 

To try some other HBN would have been my next step, but figured it wasn't worth the hassle.

 

Picture of 7mm 175 ELD X's both HBN treated, one seated and pulled. 

[gruntus]

A lot of helpful information here:

 

https://www.longrangeonly.com/forum/threads/hbn-bore-treatment.1796/

And some infomrational videos from Broz here:

https://www.youtube.com/watch?v=_yoinNhCqHg&t=567s