Gunsmiths or any one else....
I need to get one of my rifles down to bare metal that is blued...how does one strip the blueing off ones action and barrel

Daniel

Several ways; and two methods; mechanical and chemical.
Use abrasive paper, sanding or polishing belts and pads,
Sand blasting with your choice of grit media. but the easiest way is chemical; any acid will do it, and there is a product called Steel White. Once you remove it, then the bare surface needs to be polished to whatever texture you want, from high gloss to rough sand blasted. Remember,the appearance of bluing is dependent on the polish, not the blue process.
Bluing is easy to remove, but why do you want to do that?

Im looking at getting my barrels coated /treated with black nitride...barrel life is significantly pro longed

thanks for you help
Daniel

Are you doing the black nitride work yourself or are you sending it out? Might possibly need a source for this work myself.

Rustoleum that I think you can get in the USA and Australia strips rust (and rust blue) without harming any good metal. I have used it very successfully removing rust from moulds.

JIM
you cant "black nitride" your self it has to be done by a company that specialises in it...there are a number in the U.S here in Australia there are only one or two
In the U.S H@M PROCESSING PH 330 745 3075 do black nitriding

Indeed, didn't see you're in Australia, thanks.

Melonite/Black Nitride should only be done when the barrel is NEW. Otherwise, it can create more problems than it solves. Live with what you've got When you re-barrel, THEN think about Black Nitride.

Silvers
that's interesting...I heard that its good to put 60 shots or so through the barrel to run it in
Daniel

I rely on what I see through the bore scope. I only use hand lapped barrels and there really is no 'break-in' to speak of. if a solid pilot reamer is used for chambering, there will be radial marks left where the pilot end road. These need to be shot over until smoothed or polished out so they do not collect bullet jacket. All of my reamers have removable pilots and do little to no damage when properly sized for the bore. I have some chambered with no pilot at all using a bit of a different method that works well. But the point is, with a good hand lapped barrel there should be few if any flaws that need to be shot over to burnish over. Some say 20-50 or 60 shots, I go by what I can observe with the bore scope. Some I have only fired 2-3 times, other maybe 10, but never have I had one that need 60. No fire cracking at the throat should be present before sending off for nitriding. Those with 60 might be OK, but I'd bore scope so I wasn't wasting my money. Also, the barrel needs to be squeaky clean, inside and out before treatment. All bullet jacket and any other fouling needs to be removed completely. I only have barrels that have been chambered for those high intensity cartridges nitride, you know, those that are claimed to be "barrel burners". Black nitriding does increase surface hardness and with this comes ease of cleaning, the surface is hard enough the fouling doesn't stick/adhere to. I'd not bother to have a .308 or 30/06 barrel treated or a hunting rifle that that would only be shot maybe a half dozen time per year. If I had a varmint rifle that I'd plan on hunting prairie dogs with, that was chambered in 22/243, I'd have it treated. If I was building a target rifle that would see many rounds, I'd probably have it treated. There are no hard and fast rules when it comes to which chambering to have treated. The hard and fast rules are as I stated above, hand lapped, no burring where the pilot was at, squeaky clean before treatment. I have several rifles with nitride barrels. The finish is nice, close to some rust blues, and I see no down side when it comes to accuracy. To remove the bluing, remove from the action, you'll only send the barrel anyway, put the barrel on the barrel spinner and head for the belt sander. A 320g. belt will leave a suitable finish for nitriding .

butchlambert has some good info about black nitride, maybe he'll chime in and share what he has.

You need to ask your applier about it; realize that your bore has been blued as well as the outside; how are you going to remove the blue from inside the bore?
Ok, so you put 60 shots through your barrel; now you have a blued bore, with copper on it.
Ask the place that is doing the nitriding what they need.
Oh, for me, black nitriding is more snake oil pawned off on the shooting public. Others might think differently.

quote:

Originally posted by dpcd:
Oh, for me, black nitriding is more snake oil pawned off on the shooting public. Others might think differently.

I'm holding off judgment on nitriding the insides of bores. No one has done much testing to see how well it works in gun barrels. Unlike cryo treatment you can actually measure the harness change in the surface with a common Rockwell tester or a file after treatment. Something definitely makes the steel harder on the surface. I know that it works on tooling. What I also know from the oil and gas machining industry is that there can be some slight dimensional changes. How much growth per inch? I don't know. How well it stands up to heat, I also don't know. It's too new for me to recommend unless you want me to recommend the latest, hare-brained-idea.

I used some black nitrided (inside) tubing to build some air cylinders and it worked out well. Customer thought it was just as good as chromed but I never got to see them when they wore out so I can't really say. Had some rifle bolts black nitrided to make them "slicker" to operate and that worked. Regards, Bill.

dpcd

i was told you can remove the blueing from inside the bore with chemicals...

Battery acid will remove bluing instantly without any pickling effect, just rinse thoroughly with water and protect from rust until ready to nitride.
Try it on a small patch first to see that you are happy with the result.

EAGLE
if memory serves me right, is the acid that is used in batteries HCL hydrocloric acid???

coke a cola, salsa, seems that blood does it, at least if i get critter blood on my guns...

and VERY weak muratic (swimming pool) acid -- though this does etch them

quote:

Originally posted by M 98:
EAGLE
if memory serves me right, is the acid that is used in batteries HCL hydrocloric acid???

H2SO4, not HCL

Bluing is rust ( well, a form of rust) and so a phospohric acid based rust remover will eat it right off.

I had a barrel QPQ nitrided for rust protection more that surface hardness, worked very well.

The QPQ process ( Quench, polish, quench) gives a very nice glossy finish that sort of looks like hot blacking.

Sure, any acid will remove bluing. Yes, even Salsa. BUT, most of them you don't want inside the bore.
Battery acid is Sulfuric acid, as above. Don't use that in the bore.
Ask the applier what they need.

Muriatic acid diluted with about 6 parts water will remove most bluing with very little etch.

Dropping the part in a weak baking soda solution after the blue is gone will neutralize the acid

If it were me, I wouldn't have this sort of work done, unless the company had a reliable and proven system in place for cleansing and removing impurities prior to them messing with it. All of these wonderful suggestions are - - - - - - - WONDERFUL and it's good of people to take the time. But they are, by and large, experimental and may not be correct for what the application requires. I'm a firm believer in (LEAVING IT TO THE PRO'S) And if they aren't pro's, I don't leave it with them.

Just a thought.

quote:

Originally posted by speerchucker30x378:


If it were me, I wouldn't have this sort of work done, unless the company had a reliable and proven system in place for cleansing and removing impurities prior to them messing with it. All of these wonderful suggestions are - - - - - - - WONDERFUL and it's good of people to take the time. But they are, by and large, experimental and may not be correct for what the application requires. I'm a firm believer in (LEAVING IT TO THE PRO'S) And if they aren't pro's, I don't leave it with them.

Just a thought.

Do you mean home stripping of bluing or the nitriding Speerchucker?

quote:

Originally posted by Ghubert:

quote:

Originally posted by speerchucker30x378:


If it were me, I wouldn't have this sort of work done, unless the company had a reliable and proven system in place for cleansing and removing impurities prior to them messing with it. All of these wonderful suggestions are - - - - - - - WONDERFUL and it's good of people to take the time. But they are, by and large, experimental and may not be correct for what the application requires. I'm a firm believer in (LEAVING IT TO THE PRO'S) And if they aren't pro's, I don't leave it with them.

Just a thought.

Do you mean home stripping of bluing or the nitriding Speerchucker?

Well, I would hope that they had a method of doing all of the prep work themselves, both inside and outside before doing their process. Like bluing and painting, the prep work separates a good job from a bad job. Just saying that they are going to dump it into their salt bath and it will do wonderful things for you, sounds a bit fly-by-night.

quote:

Originally posted by speerchucker30x378:

quote:

Originally posted by Ghubert:

quote:

Originally posted by speerchucker30x378:


If it were me, I wouldn't have this sort of work done, unless the company had a reliable and proven system in place for cleansing and removing impurities prior to them messing with it. All of these wonderful suggestions are - - - - - - - WONDERFUL and it's good of people to take the time. But they are, by and large, experimental and may not be correct for what the application requires. I'm a firm believer in (LEAVING IT TO THE PRO'S) And if they aren't pro's, I don't leave it with them.

Just a thought.

Do you mean home stripping of bluing or the nitriding Speerchucker?

Well, I would hope that they had a method of doing all of the prep work themselves, both inside and outside before doing their process. Like bluing and painting, the prep work separates a good job from a bad job. Just saying that they are going to dump it into their salt bath and it will do wonderful things for you, sounds a bit fly-by-night.

Absolutely agreed, the polishing and prep work is the bit that takes the time and cost the money.

I had a Tikka M690 best London polished and reblued and was amazed at the work the cahp did with a draw file before he went anywhere near the abrasive paper.

I can see the difference between it and one I had polished by a belt sander jockey, real depth and gloss.

An email I received from an Army Reserve Armorer. I understand that he is one of the top AR comp. builders.

This I posted some time ago. This comes up from time to time and you can find it using the search function.

You may find this interesting, see e-mail below.

I was the Armorer for the Army Reserve Shooting Team for over a decade so I do have quite a bit of experience with both processes.

As I am sure you know, most G.I. barrels are made from chrome molly steel which is more susceptible to corrosion than stainless steel. Chrome lining is used on G.I. bores both to extend their shooting life and to protect them from corrosion that can be a problem in battlefield conditions where maintenance is sometimes sporadic or insufficient. Chrome lining does a pretty good job of protecting battlefield weapons. One of the objections to chrome lining is that it is thought to decrease accuracy. This seems to be a valid criticism and is backed up by machine rest tests I have conducted of identical barrels (same manufacturer but half chrome lined and half not).

As you are aware most barrel "wear" is in the throat area. So eventually the hot gasses from the burning of the gunpowder will eat thru the chrome lining at the throat. It is rumored that at this point accuracy will plummet but I have not found that to be true. (Or if true, it is overstated or maybe only occurs for that short period when there is both chrome and bare steel in the throat simultaneously - just at the point of initial break thru.) Chrome lined barrels can continue to shoot well for thousands of rounds after the bare barrel steel at the back of the barrel (throat) has been exposed due to erosion of the chrome lining. Another criticism of chrome lining is that it can flake off later in the life of the barrel resulting in poor accuracy. Obviously, this could also cause maintenance problems if the user is depending on the chrome to ward off corrosion and thus is careless in his bore cleaning. If corrosion is allowed to occur pitting will result and that will ruin accuracy for sure.

Barrel pitting was one of the reasons I got involved in Salt Bath Nitriding. I was loosing nearly as many expensive match grade barrels to improper maintenance (causing pitting) as I was to wear out. This was under the relatively benign target shooting conditions. Obviously given the reputation of degraded accuracy, using chrome lining wasn't an option. So for the past couple of years I have been Salt Bath Nitriding all of my match barrels and haven't had a single one exhibit any pitting. During that 2 yr. period shooters have put anywhere from a few hundred rounds to thousands of rounds on said barrels. I don't know how long the coating will persist so at this point I am still evaluating it as a preservative. I don't know what will happen in another year or two when these barrels get more wear on them. Salt Bath Nitriding goes on both inside of the bore and on the outside surface. So, instead of 2 manufacturing steps you have combined them into one. Salt Bath Nitriding doesn't degrade accuracy one iota, unlike chrome lining. This was the first thing that I verified when I began using the process. I broke in a bunch of barrels and then machine rest tested them for group. I recorded and kept the targets, cleaned up the barrels, and sent them to MMi TruTec for the Isonite process. When they came back I reassembled them on the same receivers with the same torque settings, same bolt carrier assemblies, same flash suppressors, etc. Then they were retested with the same ammo lots. NO degradation in accuracy and about a 1% increase in muzzle velocity.

Chrome lined barrels seem to clean up rather easily after a range session. I found the ease of cleaning of Isonite coated barrels to be similar to chrome lined barrels. The Isonite barrels clean up the easiest of any non chrome lined barrels I have ever used. Isonite can be applied to either stainless or chrome molly but the factory needs to know what steel you are sending them because the application process varies a bit. Again, I only have about 2 yr. of cleaning experience with Salt Bath Nitrided barrels. I don't know if the ease of cleaning will continue as the barrels get more rounds on them. Generally speaking, most non coated barrels get harder to clean later in life. Although stainless has a reputation of being corrosion resistant it isn't corrosion proof (I have had plenty of them return pitted) so I coat both my C.M. and my SS barrels. The Isonite on the outside of the stainless barrels cuts reflection down so my shooters like it.

I mentioned flaking of chrome lining inside the bore. Joel Kendrick is my contact at MMi TruTec, the company in Arkansas that does my Salt Bath Nitriding (they call it Isonite). He was mentioning using the Salt Bath Nitriding inside the bore prior to chrome lining it to get a better adhesion. He is currently working with one of the military contractors (maybe F.N., but don't quote me on that) relative to this process. He has given me permission to give out his contact information so I have cc'd him in my reply to you. He can give you the specifics of any testing and evaluation that has been done relative to this process and can give you quotes, etc. should you just be interested in the Isonite by itself as I use it.

One last quick note on chrome lining. Such barrels have the reputation of changing point of impact when heated up. I have found this to be very true. It may be due to the way the different metals (chrome molly and chrome) expand inside the bore. What ever the reason, it does happen and, again, this was verified on a state of the art machine rest. Isonite doesn't exhibit this characteristic.

I am sure you are well aware of some of the things I covered. Lacking specific questions, I just sort of used a shotgun approach which ended up being fairly long. If I left anything unanswered please feel free to get back to me. I have enabled my Spam Blocker to allow your e-mails to come in with out the automated hate responses that Earth Link sends out. I am sure Joel would also be glad to clarify the technical aspects of the Salt Bath Nitriding process. So far I am very pleased with it.

I am building a custom 40X rimfire at this time. The only way I could get a special barrel was in stainless. I wanted the rust blued look. All the metal will be polished and a Melonite QPQ process will be done.

There is another important component to all this; chrome lined barrels have to be made larger as the chrome is relatively thick. Whereas the nitride has no thickness so the barrel can be made precisely to start with. That is the reason that chrome lined barrels are not as accurate.
I have much experience with the M256 Tank Cannon, 120mm Smooth bore. Chrome plated. Cost is $100K each. We can see the same effects in it as a rifle barrel, only much much faster as the tube life is measured in the low hundreds of shots, depending on ammo. The chrome is burned off at the breech, and the issue is one of accuracy degradation, and equally important, reduced velocity.
I'll tell Benet Labs to look at nitriding them. but any change like that would entail a multi million dollar research project.

Having never had much interest in it until this was brought up. After a bit of quick reading it seems to be the same, salt bath case hardening that has been used on machine parts for years. Just with some new names and new techy catch words. But then again, I don't know much about salt bath case hardening either. But learning is a good thingy ! ! !

http://www.northeastcoating.co.../salt-bath-nitriding

Right; it is not new.
I have zero interest in it and have already spent more time on it than anyone should.

Naval Jelly will take blueing off quickly and won't damage the metal surface (as long as you don't leave it on too long).

Yes it will; naval jelly is phosphoric acid; I, personally, do not want my bore phosphated, no matter how lightly.

Barrel wear? How many rounds do you think it takes to wear out a barrel?

When I shot highpower the answer was about 5,000

that's true for both .308 and 5.56 somewhere around the 5,000 round count the barrel would no longer hold the 10 ring at 600 yards. At 200 and 300 yards it had virtually no affect on my scores. I wore out 5 barrels shooting highpower and many of them could be re-used on other guns as plinkers or other competitions not requiring long range accuracy with no issues.

If you QPQ barrel you might get another 1,000 or 2,000 rounds off it MAYBE...but once the throat starts to go the lining has almost no impact on barrel life and long range accuracy.

I shot Kreiger, Obermeyer, and Douglas Match grade barrels...make or material (stainless or chrome moly) didn't matter within a few hundred rounds...at 5K they all went south. The Kreiger and Obermeyer barrels cleaned up easier. But they shot about the same as a Douglas air gauged barrel and there was no discernable difference in barrel life.

Most people can shoot an unlined barrel for hunting purposes to 10,000 rounds. 10,000 rounds of hunting reloads will set you back $2,000 to $3,000 if you don't reload its closer to $8,000-$10,000. If you can afford to shoot that much having a new barrel screwed on is a $300-$500 deal depending on what kind of gun/barrel you have/want.

I wouldn't mess with QPQ on an existing rifle...hard to justify the expense for the benefit for 99.9% of all shooters.

quote:

Originally posted by dpcd:
There is another important component to all this; chrome lined barrels have to be made larger as the chrome is relatively thick. Whereas the nitride has no thickness so the barrel can be made precisely to start with. That is the reason that chrome lined barrels are not as accurate.
I have much experience with the M256 Tank Cannon, 120mm Smooth bore. Chrome plated. Cost is $100K each. We can see the same effects in it as a rifle barrel, only much much faster as the tube life is measured in the low hundreds of shots, depending on ammo. The chrome is burned off at the breech, and the issue is one of accuracy degradation, and equally important, reduced velocity.
I'll tell Benet Labs to look at nitriding them. but any change like that would entail a multi million dollar research project.

I've got 10 years in M1 and M1A1 tanks. The chamber pressure on these rounds is 83,000 to 92,000 psi. It makes most firearms pressures look like bb guns. Also the Effective Full Charge barrel life on a 120mm (smooth bore) tank cannon is 1,500 rounds! Not really a great comparison to a hunting rifle where the chamber pressures are rarely over 60,000 psi...

Not ragging on you...but its not a great comparison...especially since all the ammo is fin stabilized..

quote:

Originally posted by M 98:
EAGLE
if memory serves me right, is the acid that is used in batteries HCL hydrocloric acid???

As others have said battery acid is diluted sulphuric acid. Only reason I suggest this is that many years ago a car battery I was transporting to a clay target club tipped over in the tray of my utility onto a foam mat I had sat it on. Unfortunately I also had my Miroku O/U shotgun laying on the mat and by the time I got to the club, about 10 mins from home, all the bluing down one side of the barrels had disappeared and the silver nitride action looked terrible, all grey and dull. Dunked the whole gun into a barrel of rainwater at the club, dried off and did my shooting for the day. Back home stripped the gun, stripped the rest of the blue from the barrels with the same acid, flushed and neutralised and then had them reblued. The acid over that short period of time had not affected the highly polished finished.

A very light rub using fine steel wool soaked in WD40 on the nitride action restored it like new with no lasting effect on the polished finish. The gun is still like new nearly 30 years later.

I guess I'm part of the .9%. A top grade BR barrel loses it's accuracy at roughly 1000 rounds. I can get 5000 rounds on a Melonite QPQ barrel.
What if you are building a top of the line rust blued, engraved custom and the only barrel that you can get is SS? I'm doing a 40X rimfire custom. Vardy wood, Kobe carving it,40X guru, Gene Davis doing the metal work, and a special barrel from Frank Green at Bartlein. It is an 8 groove, LH gain twist barrel. What you do is send it the Roger Kehr for engraving and then off for Melonite.

Mr Ky, the analogy is valid; what I am pointing out is the the wear on chrome plated bores is greatly accelerated in the M256 due to the factors you state, and it can be seen far sooner and more evident than in a rifle barrel. EFC values are doubled for the newer ammo. The principles of shooting bullets down bores is the same, you are just larger in scale, shooting 17 pounds of propellent and going at close to 5000 fps.; smooth bore is irrelevant. I have experience on both ends of the M256, from manufacture, through the supply chain, and at the end user level. I was just saying that if nitriding is so good that maybe we should do that on tank cannons, and I am going to tell PM-TMAS to look at it. It will never happen though.

The various forms of nitride do some things well but they aren't magic.

It does provide improved corrosion protection and it can prevent things like cleaning rod damage.

It will not prolong your throat life. Dave Tooley did some borescope pics of this. The gist is that it can't alter the melting point of the steel. The crackled look at the throat is happening because the burning propellant is above the melting point of the steel. Add in some friction, carbon getting ground into softened steel...and you get throats that look like a dry lakebed.

They did a bunch of AI barrels on precision rifles and found that there was no meaningful gain in barrel life related to round count. The throat still got chewed up for the same reasons.

It does provide corrosion resistance though...

There were some other pitfalls...things like break in prior to doing it, residue in the bore after having it nitrided (depending on the method used), dimensional shift on some barrels, and so on.

quote:

Originally posted by lockingblock:
The various forms of nitride do some things well but they aren't magic.

It does provide improved corrosion protection and it can prevent things like cleaning rod damage.

It will not prolong your throat life. Dave Tooley did some borescope pics of this. The gist is that it can't alter the melting point of the steel. The crackled look at the throat is happening because the burning propellant is above the melting point of the steel. Add in some friction, carbon getting ground into softened steel...and you get throats that look like a dry lakebed.

They did a bunch of AI barrels on precision rifles and found that there was no meaningful gain in barrel life related to round count. The throat still got chewed up for the same reasons.

It does provide corrosion resistance though...

There were some other pitfalls...things like break in prior to doing it, residue in the bore after having it nitrided (depending on the method used), dimensional shift on some barrels, and so on.

You are wrong.