I'm rust bluing another barrel - this time a .22 rf. I have been having a fit plugging the barrel to avoid damaging the bore with corrosion. I have used wooden plugs but on such a small bore, they have a habit of breaking off at the muzzle or breech. Extraction is ugly! Any better ideas?

On a .45, I used rubber plugs that were fitted with brass screws that would expand the plug as the screws were turned. This was great, but there is no version of this for a .22 that I can find or figure out how to make.

I know one gunmaker varnishes his shotgun bores before bluing (and plugging too), but how to remove the varnish? And this is a target rifle, hence maintaining a perfect bore is essential.

Brent

I don't know any professional bluers that worry too much about the rifle bores while bluing. A couple of coats of lacquer will protect the bore plenty good enough. The barrel steel is 212 degress when it is removed from the tank. The water is almost completely evaporated off by the time I am able to blow it out with clean air.

If you are really freaky about the bore you can use the small surgical tubing trick. Tie a string on one end of the tubing. Tie the other end of the tubing to the vise. Run the string through the bore. Stretch the tubing until you can slide the barrel over the tubing. When you let go of the string the tubing will swell to fill the bore. It takes longer to explain it than to do it, plus it's not needed. Just lacquer the bore and clean the barrel afterward with lacquer thinner. Good luck.

How about a bit of cold blue like oxpho or dicropan? Just wet a patch and run it through..

Great new use for the surgical tubing! I've never heard of that one...

Scrollcutters got it, just shellac or lacquer the bore and even if you slop solution into the bore, it shouldn't hurt anything. Remember, when you swab out the bore that rust you see is some of what is boiling off the exterior- it shouldn't be forming in the bore but don't let it sit in there either...

Do make a note to yourself you lacquered the bore and pin it to your collar...

Brent,

Each and every recommended practice I've ever read says NOT to plug the bores. As a matter of reference, it is a dangerous practice whenever one hot blues. I have subsequently never done so and have had absolutely zero problems.

For manual or modified hot-bluing operations, the only persnickety item to deal with is the carding of the bore. I've had good results from using a triple-ott (000) steel wool. Just ensure that the wool is properly cleaned in degreasing solvent prior to use.

If you go online to Brownell's, look at their PDF library and look for the bluing practices. They give good details on this topic.

Good luck...

Just for information...



With hot blues, the barrel should emerge from the bath at about 290-295 degrees, not 212 degrees. To some degree, it depends on the depth of blue being sought, the brand of salts used, and the metal itself, but using the Lynx-line Blu-Black solutions for instance, I have often let barrels and other parts "soak" for as long as 6 hours in the bluing salts bath. Any barrel which has been in a hot blue salt bath for more than an hour will surely come out at more than 212 degrees.



Second, some of the better barrel makers I've known absolutely would NOT let any bluing solution into their barrel bores. Paul Marquart was a good example. Mr. Marquart was firmly convinced that bluing the bore compromised accuracy of his barrels.



In fact, he has personally told me stories about barrels which were greatly reduced in accuracy by bluing the bore.



According to Paul, on several occasions, he built a rifle, test fired it for accuracy and shipped it to the owner unblued. (He didn't like to do that, but would, if the owner insisted.) Then some time later, he would get the rifle back, with complaints about its accuracy.



He would test fire the rifle, and sure enough accuracy would be lousy. On examining it, he would find that the bore had been blued. So, he would re-lap the barrel to a sightly larger, but uniform very slightly choked diameter, and accuracy would return. He always used to gently curse guys who would try to save a few bucks by getting a local 'smith to blue their barrel without the knowledge or equipment to do it without bluing the inside of the barrel. (And, as Paul was very religious and gentle, and virtually never swore about anything else, that is a measure of how deeply he felt on the subject.)



Paul himself, never blued barrels, so he was not just trying to get the bluing business. He was trying to give the customer the most accurate rifle he could. He always used one man, whose name I forget, from Cornville, Arizona to blue his barrels and/or rifles. That man ALWAYS plugged the bores with rubber plugs held in place by a long, small diameter, threaded rod through the barrel.



Every rifle I ever got from Paul shot very well, and none of them had blued bores. Of course, they might have shot just as well had the bore been blued, I have no way of knowing. but I do know Paul would have had a large coniption fit had they been blued on the inside...



Best wishes,



AC

Assuming the question is limited to rust blueing (as was the question), it temperature that important?.

Thansk for the posts guys. The rubber tubing idea is quite innovative but for a .22 rimfire??? Hard to imagine how one could stretch it enough and get the first part of it started. Interesting idea.

As for plugging vs not plugging. Most of the folks that I know of who don't bother with plugging and claim it does not matter are not concerned with accuracy. Oh they are to a point, but they are not worried about benchrest accuracy. This barrel happens to be a from a 13# Ballard rifle that gets a lot of bench time. Accuracy really matters.

The other thing I note is that most really finicky bench shooters use stainless, primarily to avoid the problems of bluing. I hate stainless - on a Ballard it would be worthy of capital punishment. So, I need to figure how to blue this.

finally, most of the better gunsmithing books I have seen referenced and many of the best gunmakers I know of seem to plug the bores and some coat them with varnish also.
With the bigger bores and shotguns, plugs are easy, but with .22s it gets a bit tougher to find a good strong plug or a well fitted rubber one.

I would never do hot dip with any of my guns. This is rust bluing only.

Brent

Temp is probably not very important at all, with either type of bluing. Any temp above about 130 degrees F will cause rather rapid evaporation of any moisture. (Home clothes dryers, for instance, commonly have 125 F degrees as their "low" setting, 130 F as "medium", and 135 F as "high".)

The important point is that some really good barrel-makers believe that, if at all possible, the bore should NEVER be blued. All bluing is an oxidation (rusting) process, so all bluing oxidizes the metal it touches, whether using hot salts, or some cold process.

If the oxidation could be controlled within the bore so that it was perfectly uniform, it might not hurt.

But, with hot processes in particular, a very saturated salt/water mix is used. The mix is so saturated, that temp is controlled not with the heating element (gas burner, whatever), but with a constant slow trickle of water into the tank to offset evaporation and keep temp constant.

The heavy saturation also means that undissolved salts may find their way into the bore and "attach" themselves to particular spots in the barrel via sedimentation. If there is no way to keep the "flow" of salts moving through the barrel, this MAY result in "spotty" areas of different oxidation depth within the bore, which is what Paul Marquart felt caused the barrel to need re-lapping to restore its accuracy.

If bore bluing can be prevented with varnish in cold bluing, then fine, plugging the bore probably isn't required. But, if hot salt blue is to be used, varnish by itself may not work, and plugging can be and is used to prevent the hot salt solution from entering the bore.

AC

I really didn't ask my question as clealy as I should have. I was curious as to whether there was a minimum temp to convert ferrus oxide (red) to ferric oxide (black/blue). Just a mental exercise.

Tiggertate

I don't know what the minimum temperature is. I immerse my parts in a hard rolling boil.

#1 I want the water to evaporate as soon as I pull the part out of the water.

#2 In the real world of gunsmithing it is impossible to get the metal surgically clean. If there is a minute amount of oil floating on the water, I want it on the side of the tank not in the middle of the water where I am pulling out the metal parts.

Great point. In another lifetime I had occaision to help build a home made vat for boiling dirty engine blocks. We cut the top out of a 55 gal drum and installed an electric hot water element in the bottom under a rack and filled it with water. We bought soda-ash from a drilling mud company (extremly caustic) and voila, instant death to oil, grease and dirt. I have been often been tempted to try a variant to clean/degrease gun parts before rust bluing, just never took the time to experiment. I have enough projects on the kine now to investigate and I'll post the results.

Less than boiling water will convert the red rust into blue/black rust but not evenly, deeply, thouroughly. I know this from not being patient enough to let the water come to a rolling boil and/or trying to heat the tank with a single burner set up. You need to see bubbles coming up from the bottom of the tank vigorously.

Allow the water to come to a full boil. Shellac the bore and allow it to dry- You'll be fine...