I just read thru a thread, on another board, where one is saying he wouldn't blue a freshly cut crown on a barrel as it would hurt accuracy. I know what I think! Just interested in the views concerning bluing and accuracy here.

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I just read thru a thread, on another board, where one is saying he wouldn't blue a freshly cut crown on a barrel as it would hurt accuracy

Say what?

Well I don't agree. Hot blue for example is nothing but a stain. Even rust bluing "unless you go out of your way to damage the crown" wouldn't have an impact.

Sounds like B.S. to me.

For the record, I don't think any bluing, properly executed, will have any negitive effects. Must be one of those "old wives tales", 'cause I've, personally, never had any problems, and I've blued quite a few.

Does he offer any factual evidence to back up his claim? I'm bettin' the answer is no. I've rust blued more than a few barrels and barreled actions (and I don't plug the bore) and have never run across an accuracy issue. I've even had a couple of guys tell me that the gun shot better after the reblue. Go figure.

The fellow, who made this claim, is a self promoter over there and frequently "stirs the pot" with statements such as these. His claim is, "because the blueing process is a rust process, the sharp edge, of the crown, will be etched by the blueing salts."

If he's that worried about it, he could always go in with a piloted 60 degree cutter and just touch the rifling with it until it just sharpens the lands.

I have heard this before; never to blue a bore as it does etch it a bit; it is not just a "stain"; it is a caustic (lye) solution which microscopically etches the steel. As for the effect of that, I think it is BS. There is another theory that some barrel makers subscribe to that says that a bore can be "too smooth" and they are lapped with some fairly coarse grit. And they all shoot great.

If the surface or, edge of the metal is "etched" by the blueing, how come a highly polished surface still looks highly polished after blueing?

Look at it under a 100x microscope and you will see. Put some lye on steel and leave it for a day; you can see it with your eye. Bluing solution is sodium hydroxide; it turns steel black but it does slightly etch it in the process. Not enough to hurt the bore, but some people, as the OP says, say it matters.

I still say BS!

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Originally posted by DocEd:
The fellow, who made this claim, is a self promoter over there and frequently "stirs the pot" with statements such as these. His claim is, "because the blueing process is a rust process, the sharp edge, of the crown, will be etched by the blueing salts."

I thought that might be the case. Where might "over there" be ?

I think he has settled down now He was "preaching" to apparent newbys.

I always shot CM barrels for accuracy and break in before blueing (hot salts), and then again afterwards for a couple of groups. I must admit there was no change in accuracy, but the blueing removed any copper that was in the barrel. The first cleaning really was black, but the second time cleaned really easy and the barrel felt much smoother. I always theorized that the bluing
"filled" (for lack of a better term" some of the small imperfections and cleaning after 5 shots polished things smooth. The barrel seemed to be more resistant to copper fouling afterwards. Since a person is always trying to sell the rifles one builds on function and accuracy, if the groups had opened up, I would have never blued the bore.

I have never seen any difference but I have had customers who specified no blued bores. Yes, bluing will dissolve copper (and lead and aluminum and most everything else) and if there is any copper in the salt bath, it will cause streaks on the bluing.

Long ago, my Dad explained rust or caustic bluing as a conversion of iron oxide Fe2O3 into Magnatite, Fe3O4.

The former is unstable and soft-rust, the latter is stable and hard and adheres to steel surfaces quite well, unlike rust as we know, which flakes off and leaves pits.

So, if indeed some iron is sacrificed out of the steel alloy, there is some degree of pitting, but the resultant Fe3O4 is hard and tough and quite well fixed into the surface of the steel, in this case, the barrel surfaces. I suppose, if in fact the blue is indeed hard and tough, and smooth, then it would serve as a gliding surface for bullets to pass over with less roughness and more lubricity. Over done, I could see where a bad bluing job could damage a bore....

Perhaps one of our resident chemists could provide insight.

I know that salt bath nitriding (melonite etc) hardens surfaces and makes bore erosion almost a funny thing....