MYTH of Chrome lined bores busted

Status
Not open for further replies.
Gotta wonder what that barrel would have looked like it it wasn't chrome lined.

Also gotta wonder about the quality of the chromium coating on a cheap communist AK barrel.
 
Well, it can corrode, but water (the whole problem with corrosive ammo, the salts attracting water) won't make chrome rust. Come on, guys, we all remember the days when cars had chromed bumpers, don't we? They never rusted on the out-side. Never. But, rust could occur behind the chrome at the edges or around a ding/heavy scratch, such as the muzzle on a barrel. That rust would eventually cause bubbles of corrosion under the chrome and you could fleck the chrome away with your thumb nail.

I think we can safely say that chrome-lined bores are very corrosion resistant. We have to accept this because I have NEVER seen a rusted Chinese SKS barrel and those things have had all sorts of corrosive ammo fired through them. Go to the pawn shop this afternoon and check out the dusty SKS's in the corner, sitting beside the Mosins. Those abused Mosins will have rusted bores that are so bad, they look like a fat-man's navel. The SKS's won't be corroded at all. The Yugo's in the same corner will be rust-buckets, too.

I have seen this in years upon years upon years of checking out wares at pawn shops. Indeed, my sample numbers are high enough to draw a conclusion, especially in the South, with our high humidities. Chrome-lined bores do indeed allow a bore to resist corrosion, most of the time to a tremendous degree.

Ash
 
Sorry, a chromed bore cannot rust, hard chrome doesn't oxidize. It can corrode in the presence of chemicals, but it doesn't rust. It doesn't spontaniously corrode in the presence of oxygen even in the presence of water vapour.
__________________
------
Sorry, a chrome bore man not rust but in the presence of corrosive compounds ie from corrosive primers it will react or oxidize (rust is the oxidation of iron(steel) in the presence of oxygen) . If you are old enough to remember, those nice huge chrome plated bumpers on cars would oxidize and turn dull. A bit of polishing compound would restore the shine. In certain environments they would oxidize through and start " rusting" rather quickly!
 
AK rifles and chrome lined bores, sigh.
If there is so much as a trace of oxidation on the surface that is chromium plated it will continue to oxidize if oxygen is allowed to reach the affected area.
I'm sure Com-Bloc factory workers slam those rifles out and adhere to strict quality control standards too while working for all those substandard wages and having their retirement benefits cut too.
If any chromium plating is poorly applied it will flake and almost always does in any area suffering from trace oxidation.
Once that happens the corrosive effects are free to roam wherever they can find a surface they can attack.

Oh yeah, AK rifles, especially AKM stamped and rivited rifles, aren't as indestructable as some people believe.

If you really want bore longevity and positive adherence to the base metal spend the big money and have your rifle bores stellite coated.

I am going to keep my chrome lined rifles.
They will still outlast any plain carbon steel barrel regardless of your stunning observation.
 
chromium oxide

Chrome does oxidize. The chrome barrel has a thin layer of chromium oxide a few molecules thick.

The reason chrome is so prized for its corrosion resistance is that chromium oxide is very hard, durable and hard to remove by erosion.

Pure chrome, or chrome-nickel compounds cannot, by definition, rust. Rust is for iron / steel.

Any rust color in the pictures is steel corrosion, not chrome. What you'll see from chrome corrosion is pitting, similar to the pic of what used to be the barrel crown.

The guys who remember chrome bumpers are right on - the steel around/behind it can rust. Chrome corrosion will show up as pitting or even cracks.

Interestingly, if there's moisture around, the chrome will accelerate the corrosion of the steel. It really is electrolysis like lencac postulates. It's why the rusting on a bumper that causes the chrome to flake can be aggressive.

It's the moisture in the plastic bag that ruined the weapon. That's the reason for all this controversy, most of us don't store a piece in a sealed plastic bag but in a climate controlled environment. Put bags of desiccant in your gun safe. Not to say you shouldn't clean your weapons.
 
Chrome plating is a method used to rebuild the worn surface on aircraft landing gear shafts; it is very resistant to abrasive wear - it holds up better than the original "plain" steel alloy axle/shaft/bearing surface (whatever part).
The internal parts on a cummins or caterpillar fuel pump are chrome plated for wear resistance - those moving parts are very,very close tolerance; no internal seals are used on the throttle shaft on a cummins PT pump - the tolerance fit IS the seal. Throttle shafts come in 40 sizes @ 0.0001 increments - guess what I did for a living for 19 years?
Chromium CANNOT rust~ period. Not enough ferrous material to allow that.
Crappy, cheap flame sprayed or plasma deposited surface plating improperly applied in a machine shop environment can and usually does have ferrous metal induced into the chrome plating process, same goes with a tank type negative discharge deposit method. Cleanliness next to Godliness???
Never have seen any corrosion or "rust" on any of my Beretta shotguns internals- they have chrome plated bores and bolts on the semi auto's and just bores on the O/U's.
Besides, my Mini-14 and 30 never have rusted:neener:
 
IIRC chrome is used to prolong aircraft engine life. (Piston engines)

The piston-chambers (or whatever they are called) are bored out to be a bit wider and then chromed on the inside...

Also, I wouldn't rely on a chromed barrel to keep my rifle from rusting. I generally clean my firearms every time I shoot them. I haven't shot corrosive ammo yet, but I'd probably bring some soapy water and bore-snake to the range so I could swab it out a bit before I took it home and gave it a good cleaning.

Even if chrome-lining has no advantages (which is does have advantages), it doesn't hurt the rifle....
 
Slugless beat me to it. It is the thin layer of chrome oxide that forms on the surface that makes stainless steels corrosion resistant. Aluminum also forms an aluminum oxide coating on its surface, but it isn't near as hard as chrome oxide.

There are compounds and chemicals that can attack that chrome oxide layer and allow corrosion of the metal underneath. Chlorine for example.

For any corrosion resistant coating, as mentioned above, any scratches or flaws that expose the metal underneath will lead to corrosion in the right conditions. This applies to chrome plating as well as paint.

I agree with one poster on the first page: I have never heard anyone say a chrome plating bore is corrosion-PROOF. I have heard yahoos mouth off about other things related to guns quite often, I don't necessarily believe them (or even try to argue with them for that matter).
 
As several have mentioned you will not see chrome itself rusting.... What caused the problem here is that a weapon barrel is not fully sheathed in chrome, that is the whole point, in this case the corrosion got under the chrome lining at the muzzle, and at the gas port the rust literally destroyed the steel as it traveled under the chrome and as the blistering continued the very thin layer of chrome was reduced to shiny shreds in the muzzle pics if ya look ya will notice a few of these bright flecks thats what was left of the chrome.

The gas port is drilled right through the chrome when the gas block is installed leaving an access point for corrosion to start, the muzzle is not chromed past about 1/16" into the crown area the rest is standard steel, having a threaded muzzle device creates a high pressure area which is going to get residue blasted into those threads with each shot, if not properly cleaned your bore will rust regardless of chrome lining or non chrome lining......

This customer wanted me to replace it with the hammer forged barrel for the accuracy, I simply turn back the shoulders on the Yugo barrel to match a standard AKM and walla.... the process of hammer forging makes for a much harder barrel as well as a more consistent barrel he decided if its gotta be rebuilt then he wants to go for accuracy potential, the button rifled barrel is softer steel, this is necessary in order to drag the button through creating the rifling with the hammer forged barrel they take a larger harder chunk of steel and place a mandrel inside of it then beat it with many thousands of hammer strokes condensing the steel around the mandrel which is made to a very precise dimensions impressing the rifling into the steel as its compressed by the hammer blows its then turned on a lath to get the external profile needed versus relying on how straight the drill bored the center of the barrel stock on a standard button rifled barrel etc...

If cleaned properly the harder steel will be a lil more resistand to normal corrosion than the softer steel found in a standard barrel the big advantage is in accuracy and why it was mentioned originally. NO GUN not even stainless is completally impervious to corrosion the point of the thread is for those who will tell ya that they do not need to worry about cleaning their AK as often because it is chrome lined..... WRONG

That was it
 
That rust is not due to corrosive ammo. I've shot real corrosive ammo before, and that amount of rust can show up in a few hours, after four months it would look like it was growing big fuzzy orange mold.

Wolf is not corrosive. I'll bet that if the rifle had been siezed when new and unfired, it would have exactly that same amount of rust on it.

I've fired thousands of rounds of Wolf (both the old lacquer and new polymer) and several hundred of the silver bear, with no cleaning. I do have a chromed bore, but as was pointed out, that would not stop the gas tube or slant brake from rusting. It does make it easier to clean, just a couple oiled patches and it's clean.
 
Wolf is not corrosive. I'll bet that if the rifle had been siezed when new and unfired, it would have exactly that same amount of rust on it.

I've had a mosin nagant rust on me after letting it sit overnight after shooting Wolf ammo through it (I did not shoot any surplus or any other corrosive ammo through- just Wolf). Maybe I had a bad lot of the ammo, but I won't ever trust it to not be non-corrosive again. There might also be the possibility of corrosive materials that were also sitting in the pits of the already rough barrel being drawn to the surface when the barrel heated up- its my only other explanation.

BTW, I'm not a compulsive cleaner. I've let rifles go for months or even hundreds of rounds between cleanings- never had a smidge of rust or pitting ever, with the exception of a POS remington 597 which I couldn't stop from rusting no matter how much oil I put on it.
 
I clean my Saiga after I shoot it, every time...

Not like cleaning a Kalashnikov is a Herculean task... Also a good time to teach my kids about firearms safety and maintenance...
 
As Slugless reiterated all rust/corrosion is a process called "electrolisis". It happens. Can't be completely stopped. Also I do believe that ALL primers weather new or old, boxer or berdan, ALL can start the electrolisis process to whatever great or minor degree. Point being, CLEAN your firearms after use. It all becomes moot then.

Well, I guess we beat this thread to death uh?
 
Recall that the army specified chrome bores for M16s, but McNamara's whiz kids saw this foot dragging, and veto'd the change.

If you would remember correctly, Stoner did not use a chromed bore or chamber, adn the SF folks who originally fielded the AR had no trouble. Big Army came and changed the powder from spec, did not issue cleaning kits and told the troops the gun was "self cleaning" and problems abound. People tend to forget or moit that part.

For whatever it is worth, I just read an article on barrels and it sited that it doesn't matter to have a chromed chamber becasue it doesn't take too long to shoot the chrome out. As someone mentioned chrome doesn't corrode but it does flake. Read another report that this was the cause of barrel failures in military testing, some in as little as 500 rounds of full auto.
 
The guy talking about the aircraft engine cylinders is right on. Back when I fooled with model airplanes the better small engines were abc construstion, aluminum, brass, chromium, that combination in those high reving 30,000+rpm engines and the two cycle castor oil lube allowed them to run like that and give long life.

As someone said chrome does not rust, no it oxidizes. Rust is the term applied to the oxidation of iron and iron only and depending on conditions there are two types of rust, brown and red.
 
naked prophet, that rust is after useing WD 40 trying to get the muzzle break off, it originally was the same blue fuzzy thats on the gas piston, after the brake was off it was then cleaned on a wire wheel and then more WD40 on a brass brush through the bore those pictures show the end results after cleaning and a torch to heat the brake so it could be removed with a pipe wrench.......

And that rifle sat in a shop NEW and UNFIRED with a swamp cooler running for 9 months before he bought it, before that it was a parts set cutup with a Torch and then left in a plastic bag for a few years...... guess ya don't build many AKs do ya? There are still another 43 of those NDS-1 recievered Rommanian G kit builds sitting in that same Arizona shop with that same swamp cooler pumping out moisture into the air right now that have been on those racks for the past year...... a few of em go with Don to the gun shows around the country every week to be sold........

There are another 300 of em sitting in wooden rifle crates built on NDS-3 recievers waiting for another ban to get passed..... then they will be sold at the going rate for a preban military configured AKM etc.... no rust on any of em........ guess that kinda blows that theory huh?


As far as Wolf being gauranteed non-corrosive......... ya just keep believing that , I have a 5 gallon bucket of corroded wolf cases (the inside of the cases, the outsides are clean) that were collected up after a training shoot we did at the Catalina Pistol club range with 3 of my my NFA registered AKs for the Pima county sherifs dept...... that particular lot of ammo (5,000 rnds) had 75% of the cases start showing corrosion within 4 days of sitting outside in ARIZONA we are not known for humidity down here in case ya weren't aware... the AK that barrel came outa it was bagged and stored in a Pima county Arizona evidence room, which BTW is cooled with Swamp coolers instead of AC as I found out yesterday well at least most of the year to save $$ when it gets to monsoon season barametric tampers close the cooler ducts and the AC system comes on line during the humid months......


ya might have fired thousands of rounds of Wolf ammo partner but I've BUILT thousands of AKMs from parts sets ever since 1983 and even torched trunions (Before B-West started serializing the recievers in 1988 we had to cut the front trunions as that was considered to be the actual gun as it was the serialized part, B-West convinced the ATF that the sheet metal was actually the gun so we got to start importing the trunions intact and just lose the shettmetal etc.. torch cutting promotes oxidation) then sealed in plastic bags and stored for decades has never resulted in that same blueish oxidation ya see on the face of that gas piston, thats EXACTLY what the results of corrosive primed ammo results in....... Anyone here who has ordered a T-53 chinese Mosin M44 from Omega can show ya what the rust looks like from being stored in Arizona without being fired through the humid monsoon season at the same shop...... none of em have any rust looking like the blue cr@p on that gas piston when those T-53s ship and they been stored there for 18 years! Same building same conditions etc...


OH and BTW, There is the lil issue of there not being any trace of rust on the rest of the gun...... anywhere so your rust that would have ocured unfired and new is really special right? it only effects the bore, the muzzle device, tha gas port/block and the face of the gas piston?????? do ya wanna think on that a minute or two and Edit your comment above to look less foolish?
 
Last edited:
Ok, so the pics show corrosion outside the barrel bore...

Pray tell, where are the pics of the inside of the corrosion inside the bore and chamber end? :confused:

And if the corrosion got underneath the chrome lining at the muzzle end, that really speaks more to the quality of the chrome lining process in the barrel factory vs. that particular metal's corrosion resistance, wouldn't you say? :scrutiny:
 
.... no rust on any of em........ guess that kinda blows that theory huh?

No. It only means that the guns you had didn't rust, and the gun that did rust was in a different place. And no, I've never built an AK, not that it's relevant.

As far as Wolf being gauranteed non-corrosive......... ya just keep believing that

Didn't say guaranteed. Just said the thousands I fired were not corrosive, and the corrosive rounds I've fired were far more corrosive than your pictures show.

I have a 5 gallon bucket of corroded wolf cases (the inside of the cases, the outsides are clean)

Of course the inside is corroded and the outside is not. The outside is polymer coated and the inside is bare steel. Bare cheap steel, without a hint of chromium or other rust-inhibiting alloying elements.

that particular lot of ammo (5,000 rnds) had 75% of the cases start showing corrosion within 4 days of sitting outside in ARIZONA we are not known for humidity down here in case ya weren't aware.

In case you weren't aware, moisture or humitidy isn't required for corrosion or rust. It helps, but is not necessary. How about you wash out some Wolf cases thoroughly, make sure all "corrosive" residue is gone, then dry them out thoroughly. Set them, in the same conditions, outside and see if there's a difference in the rust.

Oh yeah, and in case you weren't aware, there is significant humidity in arid regions during certain times of the day - you do still get dew some mornings, don't you? In fact, if I remember correctly, condensation from dew (which will form more heavily on metal objects due to their higher heat capacity) actually exceeds rainfall for much of Arizona.

ya might have fired thousands of rounds of Wolf ammo partner but I've BUILT thousands of AKMs from parts sets ever since 1983 and even torched trunions then sealed in plastic bags and stored for decades has never resulted in that same blueish oxidation ya see on the face of that gas piston, thats EXACTLY what the results of corrosive primed ammo results in.......

Really? Cause all the rust I've seen from corrosive ammo has been orange. Granted, I've only fired old Czech corrosive 7.62x54R and Yugo M67 7.62x39, but those both caused orange fuzz if I didn't clean them immediately. Never had blue corrosion on my gun unless... unless... they had copper residue in the barrel, and I used a COPPER SOLVENT that turns the copper residue green. I'm willing to bet that he cleaned the gun before shooting it, and there was some residue left. Or maybe he lubed the gas piston with Hoppes #9, that will turn copper and brass a nice green color.

OH and BTW, There is the lil issue of there not being any trace of rust on the rest of the gun.

Well, you didn't say there wasn't rust anywhere else in your original post.

anywhere so your rust that would have ocured unfired and new is really special right? it only effects the bore, the muzzle device, tha gas port/block and the face of the gas piston?

Interestingly enough, when firing corrosive ammo, I've never had the bolt face rust on me. Yet the bolt face is rusted in your picture. Also, the stainless gas piston hadn't rusted on me either - even after a few days in corrosive salts.

The really odd thing is that the corrosion is blue. That indicates that he used a copper solvent on the gun. Probably lubed it with Hoppes #9 which is a weak copper solvent. It'll turn copper and brass a nice green/blue color, like what you see on your piston there.

And interestingly enougher, it might also strip chrome plating from the bore! Did you know that some chrome plating is actually attached to a thin layer of nickel which is deposited over copper, which is attached to the barrel? Dissolving out that copper will make the chrome flake off. And that's what looks like happened to that barrel, in addition to the rust.

do ya wanna think on that a minute or two and Edit your comment above to look less foolish?
 
Gewehr98, look at the new bore beside the Rommy bore, notice the light, now look at the rommy bore notice the rust all the way back to the gas port And the total absence of light......

the chamber end was fine it was the area front the gas port to the muzzle that was ate to crap.......

But hey don't clean your AK enjoy life......... it won't be my problem partner it will be yours.......

The repair on this rifle is going to cost the owner $237.75 if ya don't mind trashin your guns its no problem for me at all..........
 
Naked prophet, I can't get that quot thing to work but

"In case you weren't aware, moisture or humitidy isn't required for corrosion or rust. It helps, but is not necessary. How about you wash out some Wolf cases thoroughly, make sure all "corrosive" residue is gone, then dry them out thoroughly. Set them, in the same conditions, outside and see if there's a difference in the rust."


In that same bucket are other identical WOLF cases from another AMMO lot which have no trace of the same corrosion except where they contacted a corroded case all fired at the same time and all picked up at the same time.....some are primed corrosivly and some are not it all depends on if they got a good deal on the primers then they get used..... ya can have 3 loaded rounds outa 20 in a box turn out to be corrosive primed there is no fixed way of knowing as all the primers get mixed dureing manufacture. I've been an importer and appraiser for 14 years with onea the largest milsurp importers in the country....... I know EXACTLY what your Wolf ammo "might" get primed with........ have ya ever even been to Russia? ANYWHERE in Europe dealing with ammunition vendors or arms dealers?? oh well I have..... ya wanna believe your Wolf is totally safe all the time thats up to you and its your gun...... don't bother to clean it thats YOUR CHOICE

Never seen a rusted corroded bolt face? Ya must not do to awful much shooting or haven't had much experience with a variety of milsurp weapons, its pretty common, magazine wells and feed ramps also ya see when that fired case gets slammed into the ejector that residue gets scattered all inside the front portion of your reciever, to a much lesser degree than the bore but ya will always especially with a semi auto or full auto have corrosion present there as well thats why your told to clean out the reciever, the mag well and the Bolt face...... if a primer gets pierced it will be MUCH more pronounced as then a nice healthy blast of salts gets to the bolt face and front of reciever etc...

As for him cleaning before shooting etc.... no he did not, he stopped in at the Shop, he is a friend of the owner of the shop, he bought the rifle which was randomly taken off the rack, he asked about AMMO and where to get some, I gave him 5 Hungarian 20 rnd magazines from my case of em that are already loaded by myself just for function testing AKs with, Don let him have the Ammo and mags at a "huge" discount hell less than he sells the mags for but... Anyhow the guy lives out in Three points he stops on his way down his own road to his house to test fire his new toy...... a deputy hears the last few shots and goes to investigate....... gun goes to jail customer gets cited

the gun was dry just like all of the others still sitting on the same rack, the ammo is the same stuff we bought a pallet of last year for the machine gun shoot at Knob creek......

EDIT, BTW that is an original gas piston, the originals have an iron core which is exposed at the center the chrome plating only covers the head for about 1/8" the circumerance and then the step itself this is why ya are sposed to clean it all, these rifles are all setup with Ironwood designs stocks and pistol grips so the gas piston didn't get changed for stainless USA ones as they aren't needed for compliance with 922R as far as the corrosion colring thats the same as we get from most out here in Arizonas climate, in Misouri at Knob creek we get more of a white orangish corrosion depends on what country the ammo is from and what chemicals are used in the total package of powder and primer as well as the bullet jacket and case material composites etc... a hollow point bullet with a copper jacket covering the base will leave more of a greenish corrosion as the copper in the bullet jacket is heated and mixes with the primer salts etc... an exposed lead base will result in yet a different appearance to the corrosion then end result however is always the same failure to stop it will result in pitting
 
Well, I have only fired 1400 rounds of M67, and to you that may not be a lot. I've only fired Wolf, silver bear, etc. since then (except for Win super-X for hunting). I guess I'll just take your word on it. I don't dispute that the chromed bore doesn't provide rust-proof protection - the rest is just details.
 
LOL everybody is essetially saying the same thing: clean your guns. now there's a camp that's shot wolf for years and doggedly defends its virtue. another one claims that man never set foot on the moon, it was done in a studio in hollywood. no, that rust is the wrong color.. that must be photoshopped!

anyway - where is your shop located dstorm? I'm planning a trip to AZ soon, prescott to visit J&G, and hopefully a bunch of other gun shops... id like to visit yours too.
 
Ok, let's get one thing perfectly straight...

But hey don't clean your AK enjoy life......... it won't be my problem partner it will be yours.......

1. I'm not your partner - never was, never will be.

2. I never said one shouldn't clean their AK, and I defy you to find where I said so.

3. All of my AK rifles are fed my Dillon 550 handloads, period. It's a fair bet they're non-corrosive, and have been for the 10K rounds I've made and fired so far. If my Kalashnikovs rust, it's not because I fed corrosive ammo through them.

4. You're awfully intolerant of alternate suggestions as to why that chrome lining bubbled up off of the barrel steel near the muzzle. Matter of fact, you're downright snippy to fellow forum members asking very valid questions. Is that necessary here on THR?

5. I worked in a forensics lab analyzing metals in my last career, and I'm now doing something similar with a variety of metals now in my post-retirement career. I've seen bad chrome plating and good chrome plating. Can you accept the simple fact that such things happen? I'd wager the chrome plating in the bore of my Bulgarian SLR-95 is probably applied to a lot higher standard of quality than my Romanian SAR-1. The chrome plating in the chamber and bore of my pre-'94 Colt Competition HBAR is probably better than the SLR-95's. And so it goes. Unless, of course, you like to stir the pot with such "Mythbusting" threads. In that case, carry on.
 
Status
Not open for further replies.
Back
Top