Bullet Coatings Boron Nitride vs Tungsten Disulphide

[ELR LVR]

Anyone got any comparison specs (Friction coefficients etc)
I read that...A coated film of the Tungsten DiSulphide....
....handles pressures up to 300,000 PSI.... so thats a plus in a rifle.
....Friction Co-efficient of .03 Dynamic / .07 Static) Can someone explain the dif betwen those two as it applies to a bullet traveling down a bore, when does the Dynamic suddenly become Static or vice versa
--------------------------------------------------------
I dont know about the Hex BN in that aspect there.
--------------------------------------------------------
Any emperical definitive results between the two?
Such as 500 rounds of one compared to 500 rounds of the other?
Then measured throat erosion between the two?
I only have used Boron Nitride...... so want to know if I am missing out on anything with the Tungsten...
or is it
samey same, 6 of one, half a dozen of the other take your pick kind of thing?

One reason I am wanting to know more of others experience is I recently I spoke with a guy using a 22-284 with solid coppers at 3800 fps, coating them with the Tungsten stuff, and no appreciable throat erosion.
So I need to know more now.

I know the HBN seems Not messy when handling bullets and color is somewhat clear
I like that one major aspect compared to say MOLY, I dont like MOLY much.
Is the Tungsten stuff messy, dark stains etc like Moly does
Does it buld up in the bore and is hard to get out like Moly supposedly is.
Or should I just stick with HBN, as it being good enough and no reson to experiement

Thanks all

 

[Bill Norris]

Anyone got any comparison specs (Friction coefficients etc)
I read that...A coated film of the Tungsten DiSulphide....
....handles pressures up to 300,000 PSI.... so thats a plus in a rifle.
....Friction Co-efficient of .03 Dynamic / .07 Static) Can someone explain the dif betwen those two as it applies to a bullet traveling down a bore, when does the Dynamic suddenly become Static or vice versa
--------------------------------------------------------
I dont know about the Hex BN in that aspect there.
--------------------------------------------------------
Any emperical definitive results between the two?
Such as 500 rounds of one compared to 500 rounds of the other?
Then measured throat erosion between the two?
I only have used Boron Nitride...... so want to know if I am missing out on anything with the Tungsten...
or is it
samey same, 6 of one, half a dozen of the other take your pick kind of thing?

One reason I am wanting to know more of others experience is I recently I spoke with a guy using a 22-284 with solid coppers at 3800 fps, coating them with the Tungsten stuff, and no appreciable throat erosion.
So I need to know more now.

I know the HBN seems Not messy when handling bullets and color is somewhat clear
I like that one major aspect compared to say MOLY, I dont like MOLY much.
Is the Tungsten stuff messy, dark stains etc like Moly does
Does it buld up in the bore and is hard to get out like Moly supposedly is.
Or should I just stick with HBN, as it being good enough and no reson to experiement

Thanks all

Tried both and seems they both will keep the heat down somewhat. Barrel clean up is definitely quicker with both. I favor the HBN due to the fact that the coating process is cleaner. When and if one leaves HBN going back to the uncoated bullets there is no worry of cleaning the barrel. However, it is recommended to clean the barrel well and coat bore with an alcohol/HBN saturated patch when going to HBN. There is a video in U-tube with a guy stating burn off in the barrel temps. is @ 2600 deg. vs tungsten disulphide & moly burning off at a much lower temp. I have no scientific facts of any of that info.

 

[ELR LVR]

However, it is recommended to clean the barrel well and coat bore with an alcohol/HBN saturated patch when going to HBN.

Thank you, I was hoping to stick with HBN and it looks like the best choice then for me.
When you say here ...going to HBN
Do you mean if I have been shooting coppers only then its best to
"pre lube" the bore with an HBN /alcohol patch before just jumping in an shooting them coated?
What will happen if I don't

 

[Bill Norris]

Thank you, I was hoping to stick with HBN and it looks like the best choice then for me.
When you say here ...going to HBN
Do you mean if I have been shooting coppers only then its best to
"pre lube" the bore with an HBN /alcohol patch before just jumping in an shooting them coated?
What will happen if I don't

Yea, from what I have read and gathered from others it's best to clean the bore really well when leaving the un-coated bullets and coat it with the alcohol/HBN mix just prior to beginning shooting the coated bullets. I do this and each time I clean the bore I re-coat it with the mix prior to shooting it. I have no proof if coating the bore helps or hurts anything at all and no proof of accuracy improvements. I do see a cooler barrel longer within the string of fire and clean-up of the bore is much quicker and easier than shooting un-coated bullets.

 

[ELR LVR]

Got it, makes perfect sense to clean the bare down to perfect clean metal before using them also

 

[Bill Norris]

The rifle I am now shooting the most and have tested HBN will shoot groups like this with coated or un-coated bullets @ 100 yds. Tested it with other rifles too with about the same results. That's why I can't say HBN increases accuracy.

 

[ELR LVR]

Nice group!
, I wasn't even considering it for any accuracy boost though, mainly throat erosion is all.
If the gun is built right it should shoot the same I believe coated or not, I mean guys have been shooting tiny groups for over 40 years without it.
I dont even need it for Velocity
But if it reduces internal Temps by also greatly reducing the friction, then it should greatly prolong Throat life.
Quite a few calibers like the 264 WinMag, 7mm Dakota or STW etc have fell by the wayside
mainly due to barrel life.
But may deserve another chance using coated bullets

 

[Bill Norris]

Nice group!
, I wasn't even considering it for any accuracy boost though, mainly throat erosion is all.
If the gun is built right it should shoot the same I believe coated or not, I mean guys have been shooting tiny groups for over 40 years without it.
I dont even need it for Velocity
But if it reduces internal Temps by also greatly reducing the friction, then it should greatly prolong Throat life.
Quite a few calibers like the 264 WinMag, 7mm Dakota etc have fell by the wayside due to barrel wear
But may deserve another chance using coated bullets

Right I totally understand and agree.

 

[davidjoe]

I’m enamored with HBN right now. I have invested in a novel bullet and cartridge combination that no else I know uses in string fire matches, 250 A-Tip / 300 Win Mag.

The general idea here was to eliminate frustration with first tier brass shortages, and never be wanting for boiler room. Shrinking the size of wind holds at least as well as a 7 Saum was equally important.

The bullet needed a tight twist, and the cartidge in string fire was fully capable of achieving “terminal velocity”.

HBN, sharing some credit with shorter barrels that are half an inch slower twist, has these firmly berm-bound, now.

You almost can’t pick the coated bullet up, to seat it. That is exactly the goal. Any lapse of concentration and it’s squirming loose.

1) copper fouling down;
2) heat down;
3) blow ups down;
4) barrel life, improved.

I shot this target today with HBN coated 250’s. Clearly I still need to figure out my vertical issues, possible higher charge weight on all those above group, but the velocity feature was disabled, so I’m surmising.

The way I am seeing this, the bullets make a skinny horizontal possible (for me) but HBN makes “the bullets” possible in fclass, and it had started looking bleak.

 

[ELR LVR]

I’m enamored with HBN right now. I have invested in a novel bullet and cartridge combination that no else I know uses in string fire matches, 250 A-Tip / 300 Win Mag.

The general idea here was to eliminate frustration with first tier brass shortages, and never be wanting for boiler room. Shrinking the size of wind holds at least as well as a 7 Saum was equally important.

The bullet needed a tight twist, and the cartidge in string fire was fully capable of achieving “terminal velocity”.

HBN, sharing some credit with shorter barrels that are half an inch slower twist, has these firmly berm-bound, now.

You almost can’t pick the coated bullet up, to seat it. That is exactly the goal. Any lapse of concentration and it’s squirming loose.

1) copper fouling down;
2) heat down;
3) blow ups down;
4) barrel life, improved.

I shot this target today with HBN coated 250’s. Clearly I need figure out my vertical issues, possible higher charge weight but the velocity feature was disabled.

The way I am seeing this, the bullets make a skinny horizontal possible, but HBN makes the bullets possible.

Niiiiice, What velocity do you suspect you are driving the Atips at? The 250 is a hefty bullet.
(Likely more than would normally be possible?)
What yardage was your shown target shot at?
---------------------------------------------------------
(Blow ups down is something very beneficial I had not really taken that plus HBN into the equation and now believe I can use bullets I would not have normally been able to before ....good point made there since I always attributed that to Mfgr's advertised Jacket thickness being more the culprit. )

 

[davidjoe]

Today was all at 1,000, Houston, sea level. The display does indicate 1,886, but that is after I saved it, under my initials, and then reopened the saved target to screen shot it. I don’t think we could access velocity today, beforehand, as I tried to touch the shot and see mine. But that figure helps.

Just going off “1,886” at the target, that’s 2,850 MV, based on an .878 G1 BC. That’s at 8:30, and 30 to 40 more later on is common.

Admittedly, I upped the charge to “re-find” the HBN limit. I “kind of” wanted to lose a shot just so I’d know, but I didn’t. Zero no-reads, and the brass and primers look good.

Sometimes there’s a point where all the powder seems to burn more consistently, and it’s usually when pressure/velocity is getting up there, as opposed to the colder loads.

Yeah, it really does open the door for more combinations. I know this speed was a real problem, bare. I don’t anything about TD coating firsthand, only moly and HBN.

Another plus is that a moderate barrel cleaning doesn’t require a huge number of foulers.

 

[ShtrRdy]

I can answer your "static" and "dynamic" friction question. "Static" friction is the amount of resisting force to overcome to get an object moving from a stopped or stationary position. "Dynamic" friction is the resisting force when an object is moving.

 

[Kimber.204]

Anyone got any comparison specs (Friction coefficients etc)
I read that...A coated film of the Tungsten DiSulphide....
....handles pressures up to 300,000 PSI.... so thats a plus in a rifle.
....Friction Co-efficient of .03 Dynamic / .07 Static) Can someone explain the dif betwen those two as it applies to a bullet traveling down a bore, when does the Dynamic suddenly become Static or vice versa
--------------------------------------------------------
I dont know about the Hex BN in that aspect there.
--------------------------------------------------------
Any emperical definitive results between the two?
Such as 500 rounds of one compared to 500 rounds of the other?
Then measured throat erosion between the two?
I only have used Boron Nitride...... so want to know if I am missing out on anything with the Tungsten...
or is it
samey same, 6 of one, half a dozen of the other take your pick kind of thing?

One reason I am wanting to know more of others experience is I recently I spoke with a guy using a 22-284 with solid coppers at 3800 fps, coating them with the Tungsten stuff, and no appreciable throat erosion.
So I need to know more now.

I know the HBN seems Not messy when handling bullets and color is somewhat clear
I like that one major aspect compared to say MOLY, I dont like MOLY much.
Is the Tungsten stuff messy, dark stains etc like Moly does
Does it buld up in the bore and is hard to get out like Moly supposedly is.
Or should I just stick with HBN, as it being good enough and no reson to experiement

Thanks all

22-284 and "no appreciable throat erosion" don't go in the same conversation.
There are guys on here toasting .22 Creedmoor throats in less than 1000rds with a third less powder.
If he's using something like H4350 that is like sending 80grit blasting media down the barrel...a very small barrel, and there is no way the throat isn't moving forward regularly.

Not trying to be a naysayer - but when PRS guys are toasting 6Dasher throats in 2000rds - again, larger bore and 1/3 the powder of a .284 case - something smells fishy to me. I'd want to know all the details of his setup, load, how he's measuring throat erosion(or lack there of), etc.

I've never used the Tungsten DiSulphide, but I've had success with moly and HBN - but I don't think it was life changing unless you're running at the top end of velocities, or running long rapid strings and you're really trying to keep the heat down.

Good luck,
Let us know what you find out and decide.

 

[ELR LVR]

22-284 and "no appreciable throat erosion" don't go in the same conversation.
There are guys on here toasting .22 Creedmoor throats in less than 1000rds with a third less powder.
If he's using something like H4350 that is like sending 80grit blasting media down the barrel...a very small barrel, and there is no way the throat isn't moving forward regularly.

Not trying to be a naysayer - but when PRS guys are toasting 6Dasher throats in 2000rds - again, larger bore and 1/3 the powder of a .284 case - something smells fishy to me. I'd want to know all the details of his setup, load, how he's measuring throat erosion(or lack there of), etc.

I've never used the Tungsten DiSulphide, but I've had success with moly and HBN - but I don't think it was life changing unless you're running at the top end of velocities, or running long rapid strings and you're really trying to keep the heat down.

Good luck,
Let us know what you find out and decide.

Ok so, I believe your theory here because yes I have heard of guys toasting their barrels in less than 1000 rounds, and shooting sustained hot will really contribute to this.
I have not shot my 6x284 barrel with sustained strings of hot fire so this also cuts erosion in my case which should be taken into account for guys building an overbore and are afraid of burning out their barrels too quickly
Which I am seeing will not happen if you are conservative in how hot you allow your barrel to get.
As well, the diameter or mass of the barrel is a factor ( my barrel weighs 10 lbs so takes a long time to get hot, that was purposely done just for this reason)
.However
I went ahead and measured my throat erosion last night in my 6x284 which uses H1000 and drives 115's at 3400 fps (its a hot rod of sorts)
At just over 1000 rounds I have ( actually stopped round counts after I reached 1000 rounds because throat erosion has been so slow I dont even care now, it is likely more at 1200 rounds now)
-----------------------------------------------------------------------------------
I have only 0.010" total throat erosion from when the chamber was cut new
I actually measured twice to make sure I was correct when taking this measurement
My conclusion is it must be due to the HBN coating, (should be because otherwise its snake oil)
Before.... with naked bullets and same brand Krieger, similar profile (Heavy) barrel I had....
... 0.300" throat erosion after 1900 rounds. and velocity fell off 300 fps from 3400 to 3100
So before HBN erosion was typical for an overbore at approx .00015 round.
----------------------------------------
.00015" erosion per round naked
Vs.
10 millionths throat erosion per round with HBN
or .010" per every 1000 now
------------------------------------------
Erosion is cut by approx 1/10th with HBN coated bullets
My velocity has not fallen off and my dope chart is the same as 4 - 5 years ago
This is my most important factor, I do not want to be constantly having to readjust my dope chart

 

[ELR LVR]

Today was all at 1,000,

Sometimes there’s a point where all the powder seems to burn more consistently, and it’s usually when pressure/velocity is getting up there, as opposed to the colder loads.

Was figuring 1000, but I dont like to guess..., I like it!
And I often find the same with powder burning better when closer to max pressures
Good results there
and 2850 with a 250gr? Thats hoofing it