Home Forums Hunting & Shooting Ask The Gunwriters Does Bluing increase friction?

I was talking with a gunsmith friend last evening, and have been thinking. (I know, dangerous) He mentioned that he wants to do a test on blued barrels, hand lapping before bluing vs after bluing. He also said that he believes bluing increases friction, and if the barrel was lapped then blued, it will shoot better once the bluing wears off. Just curious about your thoughts on this, is it reasonable to think so? And if the bluing does indeed increase friction between barrel and bullet, does it not stand to reason that as the barrel is shot more, velocity will increase? Just pondering here and would welcome some input. BTW, the gunsmith is a guy who does not just believe what he is told, he tests things out and arrives at his own conclusions. He just does not do enough blued barrels to do a test as most guys that want accuracy go with stainless.

Most gun smiths use a chamber and bore plug when bluing. Since it is a type of oxidation or corrosion it is a fair assumption that it could be rougher and cause more friction but it would be difficult to test. Shooting the bore clean the difference might be so slight that the slight amount of throat erosion could off set this. This is a long way to say I don't know.

I've never heard of somebody bluing the bore of a rifle. ( on purpose, that is.) It makes no sense.

From Brownells:

When I started bluing in 1983, I started with Brownells salts and used them until I quit bluing about two years ago. That warning that Brownells published, made a lot of sense to me and I never even thought of plugging the bore ----ever! I blued hundreds of rifles and I doubt any damage or pressure increases took place. My thinking on the bluing solution inside the barrels disappeared on the first shot through the bore. I also doubt that it improved accuracy either, but plugging the bores definately improved my chances of burning the crap out of myself and everything else.
I knew a dumb-ass that splattered hot (292 degrees approx) bluing salts on his bare arms while bluing that left permanent disfiguration on his arms.
I don't know for sure, but I doubt the gun companies plug the barrels either.
I have shot unblued barrels many times after installing them. Before bluing them. Some I sighted in after the rifle was completed and I didn't see any differences in groups etc.
All I know about this subject is from personal experience, I do think that Bob Brownell knew what he was talking about.

I'd bet the government started doing this to save time and increase production. If you don't have to plug and unplug a bore it would go faster, and in the long run be cheaper. I never thought about the possibility of the plug blowing out. I just have never noticed the inside of a barrel being blued. You learn something every day. My Dad was an old time pharmacist that still did compounding when most has stopped. Several times a year, a local well-known gunsmith would have dad make up a pint of bluing from a recipe that he had. He made it for them for 40 years or more. It had some poisonous chemicals in it and required care in mixing.I don't even know if a person could get the chemicals these days. The gunsmith was known for his great bluing jobs, so it must have been good stuff..

"Tests were run by the government".....
On a scale of 1-10 how much faith do you place in the bureaucrats who selected the people who were paid to do the study?

You have a point, but are there studies that show otherwise? I am guessing this may be a pretty specialized question, maybe too far off the deep end for anything more than speculation.

I am not familiar enough with the chemistry of bluing to comment myself....

As to your question: I do not know, and have not yet looked, though I have dabbled with cold bluing in the past...

My first thought on reading the post was that maybe it fills in the surface like waxing your car...but then I recalled the thread about removing rust and a comment from Mule Deer(?) That removing rust was a mechanical process and another that bluing was a type of rust...

So I opted for a government work comment to play for time...

I think I will do some reading tonight...

Never heard of anyone plugging a bore.

Interesting.
SWDinc.com (A company that sells gun blued fasteners) indicates that hot blueing creates Fe3O4 (Magnetite) at/into the surface of the steel. Magnetometer is a rock that is magnetic......

This is really interesting with respect to a thread about a magneto-something or other velocity measuring tool, (vs. a chronograph) which some fire members have said degrades accuracy....

But that is another topic.
The sit also says that "black oxide parts have improved publicity and anti-aging characteristics due to the after-finish (oil or wax) resulting in smoother running, mating parts."

So based on the statement of a company who gets their business from the superiority of black oxide fasteners, it is still the oil which makes bullets pass more smoothly through your bore....

Hope this helps.

You may not want to be standing over the bluing tanks when the plugs blow out splattering 200 + degree caustic bluing salts all over. There is a good reason not to plug the bore when bluing.

Somewhere in my reading of JB's wisdom, he pointed out the fact that a perfectly smooth bore could actually present more friction to a bullet passing down it simply because it allows more contact between the bullet's surface and the bore's surface. If bluing "roughs up" the bore just a bit I do not believe it would have any negative effect on velocity or pressures.

If I'm understanding you correctly, you're speaking of the MagnetoSpeed chronograph. The sensing technique used by the device has nothing to do with influencing accuracy, it is due to the fact that you've got something hanging on the barrel near the muzzle interfering with normal vibration patterns.

RiverSide,
What I am thinking is that if the entire barrel, action etc is slightly magnetized and the instrument is measuring a disturbance in the magnetic field... perhaps there is a subtle factor being glossed over.
We know that an electrical current can be created by passing a metallic object through an electrical field, as well as a magnetic field being generated by a current being passed through a magnetic field ( induction) if you have read about cell phone chargers where you just lay the phone on a pad.
Perhaps the fact that the bluing magnitizes the rifle and the magnetospeed strengthens the field since the bluing will transmit the field of the magnets...we can better understand why the Magnetospeed causes issues. Perhaps it is more than the Boss harmonics issue.
I feel I am doing a poor job of explaining this, but perhaps you get what I am getting at.

Don't know about faster or easier to clean.

But when hot water blueing i never plugged the barrel or chamber.

I cleaned the bore before it was shot and never noticed anything amiss.

Ok. Sat and composed my thoughts a bit..
So a chronograph has two coils set up a few inches from the muzzle. They measure the disruption in the field between them.

Because the magnetograph hangs from the muzzle, the coating (gun bluing) may spread the field intentionally created by the designers. Since a copper jacketed round may have a current induced into it. There may be an effect on accuracy. Testing a jlead unjacketed round with this instrument may help to evaluate this.

Call it the particle accelerator effect..

Fodder for for the gunwriters..

Purely anecdotal but I’ve not noticed any impact shift with heavier barrels and the magnetospeed, for me
It’s only been observable with lighter barrels. And lots of guys have built stands for magnetospeeds and write that after doing so they didn’t notice any impact shifts. If the shifts were due to magnetic field disruption they would still show up in both the events but they dont making it more likely that it’s just due to the chrono hanging off a light weight barrel and messing with harmonics.

Also my understanding is that magnetite CAN become magnetized but isn’t always or necessary so. Just about any steel or iron can probably be magnetized if exposed to certain conditions

It would be an interesting experiment, I guess. I rather doubt that it makes much if any diffference, but I don't have any experimental evidence to back that thought up.

Bluing is really just a passivation process, in which a microscopically-thin layer of black iron oxide (Fe3O4) is developed on the surface,by the transformation of the surface iron, to give some small resistance to the development of the other form of iron oxide (Fe2O3) which is reddish-coloured and comparatively bulky - rust, in other words. The resistance to rusting really does need oil, wax or something similar to be effective longer term. Done properly the oxide transformation to form the blue should not significantly affect the smoothness of the surface, and I can't immediately see how it would increase friction.

On the other question "does it not stand to reason that as the barrel is shot more, velocity will increase?" I don't think it does stand to reason. The bullet is softer than the bore and, unless covered with grit or lapping compound it is not going to wear the bore or smooth it. I have seen barrels that have had thousands of rounds through them, but away from the chamber and throat still bear the machining marks from the day they were made. What will generally do for a barrel is either neglect (eg pitting), damage (eg rod wear, bulges) or, more commonly, erosion - the gradual washing away of the rifling in front of the chamber.My experience of the latter is that rather than making a rifle shoot faster the converse is more likely, if anything.

I don't see how the bluing plays any part in this. The Magnetospeed sensors are forward from the muzzle, and triggered by induction caused by the metallic bullet travelling past each of them.The barrel material has nothing to do with the measurement. Call it the "innocent bystander not affecting the outcome effect", perhaps?

Whilst discussing this topic a tin foil hat may be appropriate.

Dan_oz,
Granted we are probably talking about which angels dance best on the head of a pin but my thought was that the bluing might create a longer magnetic field than intended. Amplifying the Magnetospeed field...

If it is another force on the projectile than it might act similar to gravity in spindrift..

Like someone else said an interesting experiment..

Particle accelerators use magnetic fields to steer and accelerate really small things around the equivalent of a NASCAR track until they hit a target speed, then the send them down a runaway truck ramp to crash into something. I am suggesting we are talking about a really small amount of that same magnetic steering force...

Probably not germane to the op...but I was bluing a barrel yesterday, remembered this topic, and took some very precise (without an electron comparator) EXTERNAL measurements with a Swedish ten thou. mike. Tried to eliminate every variable I could think of, recorded my measurements and re measured after bluing when the temperature stabilized back to the starting test temp. You guessed it...no change. Conclusion? If there was no physical dimensional change, I doubt you could quantify a velocity change given all the variables.

Not when it's free standing...

I've fitted thousands of chromoly barrels over the last forty years and have blued the bore of each and every one of them. I do think bluing can make the surface just a little bit sticky. I once built a 35 whelen on a 98 Mauser. The rifle got iron sights and sight installation was done before blueing. When it was all done, I pulled the barrel and blued the rifle. I had a hell of a time turning the barrel in to register with the sights on top. I finally lapped the threads a bit with JB compound to set it up. GD

only time I plug the bores is when Parkerizing and plating, never blueing, tried that once

How do you say bluing creates a magnetic field? How would such a field, if it existed, "amplify the Magnetospeed field"?

What force is created? In which direction does it act? Where does the energy come from?



What you are talking about is effectively a rail gun, or coil gun. You need to pump in considerable amounts of electrical energy to create a strong enough field to make them accelerate projectiles, as well as supplying this energy in a particularly specific way. Where does the energy come from to create a strong enough magnetic field to accelerate projectiles to any noticeable or measurable degree in your blued rifle?

Thanks for the clarification. I will ask what my gunsmith does. He either uses a chamber plug or polishes it afterward as the chamber isn't blued.

Edit. This didn't come out right by by responding to each q...
Q1
Assuming that the bluing has some magnetic properties, two magnets in close proximity will constructively, or destructively interfere...

Q2
Still talking about a magnetic or current induced force here. The direction of which is probably unknowable without serious high quality instrumentation.

Q3
Except my assumption is that the force is probably not co linear with the velocity of the projectile. My thoughts tend to be that it is temporary (not constant like gravity) possibly somewhat lateral push on a spinning object. Producing the "push on a spinning toy top" analogy.....

My general interest on reading that bluing was essentially magnetite is that we might better understand the "why" of the observed group spread when using the Magnetospeed. Something to test if a gunwriter (or someone else) as a slow month and access to the right equipment.
I fear that I have distracted the OPs focus of the thread (bluing thickness) though. Which was unintentional. Just an "oh wow, that's interesting" kind of thing related to bluing.

Thanks for making me think more about the forces involved....

I have been reading with interest, although I have had to re-read some parts several times! That comment about John Barsness saying that a smooth barrel increases friction due to more bullet contact really intrigues me. It seems almost counter-intuitive to me. Does anybody know where I can find where he wrote that? Article/book? It would be interesting to see if any other gun loony agrees or disagrees with that theory. (At least I assume it is a theory??) May need to start a new thread on that!

I would have to agree with Mule Deer. You are creating MORE contact... more drag... but we are talking a very LITTLE bit. I took a 1 night a week gun course in Burlington, Iowa for a couple of years. This was a night course and really had NOTHING to do with the full time day course. The day instructor was one of the finest gun smiths and was in a lot of the gunsmith guild builds... but said he would rather go fishing... The bore was not plugged at bluing. One of the know it all students decided he knew more than anyone else and plugged a bore which blew out and sprayed it all over the place. No one plugged the bore after that. Story I got was the bluing penetrates about 1K of an inch and builds less. About first shots cleaned it all out. We would use wire and make hooks to hang the barrels from. I was about the last guy to the tanks one night an the bluing level was a little low. Not wanting to add water and have to wait till the temp came back up I tried to wiggle the support rods for a little more "DUNK" and stuck my fingers in the bluing... just about half way. YA, IT BURNED>>> BAD ! The guys made fun of me and said my hands my hands were made of cast iron as they turned red and not black. Under running water you could pour the skin on my fingers back and forth.
These discussions are fun but in the end matter way too little that we will ever notice. Ray

From this thread in 2015:

So basically why drag racers use slicks as opposed to street tires. Makes sense.

Also that hot blueing stick/penetrates better (in the absence of fire and lead)...
So the bluing coming off the inside may be related to oxidation energies...

My chemistry is a bit rusty but zinc is to the right of iron on the periodic chart. Zinc is used as a sacrificial anode to prevent rust on boat prop shafts and motors. Lead is to the right of zinc. Copper is next to zinc on the left side, but still right of iron. Perhaps under the heat of firing the oxygen if the bluing prefers to stick to copper or lead?


Dan_OZ, a cool YouTube clip for magnetic force and copper found while looking up periodic table and oxidation.....
https://m.youtube.com/watch?v=sENgdSF8ppA

Off a forum I bought a 260Remington Douglass XX blued 98 Mauser unfired Factory 22" 2# 10.5 oz = 42.5 oz $115 + $15 shipping = $130
That was cheap. These days I pay $300 and have to cut my own chamber and threads.

It seems to have a bore blued at the factory.
It gets Copper fouling in a couple groups.
It may be that the bluing helps me see the Copper.

When I clean it an shoot 100 gr bullets through the 10" twist barrel, it gets good groups.


2009 is the last time that Mauser went to the range.