Gunsmithing Barrel Coatings

[ScottWatkins]

Has anyone tried barrel coatings such as TiN or any of the other vapor depositions?
It seems this could be a huge advantage by offering less friction and a tougher surface. There would be other advantages as well depending on the coating used.
Whatcha think???

 

[ScottWatkins]

Re: Barrel Coatings

Does this idea suck or am I the only one that has thought of it?
I'd tend to think the lubricity provided by the coating would do several things. Less fouling and higher velocities/less pressure from same load.
It would also keep the throat from eroding as fast.
I can only see benefits from this. I'll look deeper....

 

[MinorDamage]

Re: Barrel Coatings

I know of people who have done IonBond on long rifles. However, as it stands, you cannot get it down the bore of the weapon which negates the "Less-Fouling/Higher Velocity" argument. It is great for the outside, just doesn't do so well at depositing on the inside of something as confined as the bore.

Josh

 

[Wheres-Waldo]

Re: Barrel Coatings

As far as your "less frictions = higher velocity" line of thinking, its backwards. If you did infact wind up with less friction for any given bullet, your velocity would drop, not increase. Powder burns relative to pressure...the less pressure, the more powder you need.

I was under the impression that Nitride coatings could be deposited into the bore though...?

(This is why you need more of the same powder to push a light bullet at X speed than you do using the same powder and a heavy bullet...heavy bullet = more bearing surface in the bore = more friction = more pressure)

 

[ScottWatkins]

Re: Barrel Coatings

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Wheres-Waldo</div><div class="ubbcode-body">As far as your "less frictions = higher velocity" line of thinking, its backwards. If you did infact wind up with less friction for any given bullet, your velocity would drop, not increase. Powder burns relative to pressure...the less pressure, the more powder you need.

) </div></div>
This doesn't make any sense to me. If you don't mind, explain further.
The way you make it sound, I could rough up the inside of my barrel and gain velocity, by increasing pressure.
I was always under the impression with a polished (or smoother, less friction) bore, velocity would increase.
Now, I understand with less friction, the pressure goes down and THEORETICALLY I could increase the charge and get even more velocity.

 

[Wheres-Waldo]

Re: Barrel Coatings

Lets have a little abstract example here...

You have in your hand two bullets, EXACT same weight, but bullet one has a larger bearing surfact than bullet two...

Bearing Surface = Portion of said bullet that comes in contact with the bore of the barrel, weather it be lands or grooves.

You load both bullets in identical cases, behind identical charges of powder, with the same primer.

Lets now take both rounds and take them out to the range and send them through a chronograph.

The loaded round containing bullet #1 (the bullet with a larger bearing surface) should chrono out at a faster speed than the round containing bullet #2.

Why this happens?

Powders burn rate is relative to a few things...
Temperature and Pressure namely.

When a you increase ONLY the bearing surface of a bullet, you increase the amount of force it takes to force it into the lands and grooves, you also increase the amount of force it takes to push that bullet down the barrel AFTER its fully enguaged into the lands and grooves.

Increased required force for that bullet = Increased friction.

Increased Required Force = Increased Friction = Increased Pressure

Powder burns relative to pressure...and since we have more pressure being required to move said bullet down said barrel, said powder burns faster...

Lets now look away from the bullet and take a look at the barrel...

Lets say you have two barrels.... Identical in every way...except...

Barrel #1 is a .308 Groove - .299 Land
Barrel #2 is a .308 Groove - .301 Land

Barrel #1 is a "tighter" bore than barrel #2...

These barrels will demonstrate the same tandancies as our bullets did in the first example....the tigher bore will take more force to have a bullet driven down it than the normal bore.

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body"> Increased Required Force = Increased Friction = Increased Pressure
</div></div>

By you coating the inside of your barrel with whatever in the attempt to achieve whatever....you wind up constricting the bore a little bit....you also MAY wind up making the surface slicker... these two effects of the coating lend results that counter-act each other...but thats not really what we are talking about here.

In the end....

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Increased Required Force = Increased Friction = Increased Pressure
</div></div>