Early Bluing Question for Mr. Beard

[togor]

This is a question inspired by the fine early modified rifle recently offered for sale both here and on other milsurp sites. What caught my eye is the barrel bluing near the early rear fixed sight base which is strapped as opposed to a solid sleeve, as shown below.
http://www.fototime.com/2AA09216AC56706/standard.jpg
Some of the barrel appears in the white, in a edge that follows the contour of the fixed sight base. I would think that immersion in the bluing tank would not result in such a contour. Could this be a case where grease or similar was applied to mount the base, and then only wiped off where easily accessible? My understanding is that sight bases were mounted on barrels while all part were in the white, and blued afterwards. I've noticed a similar contour on other photos of strapped rear fixed sight bases, but this is the best quality photo for illustrating the point.

[98src]

Certainly not Mr. Beard, But I think the answer lies in the fact that the barrels ( and rear sight base ) were blued using the rust blue method and not in hot blue tanks. The bluing ( rusting chemical ) was applied with swabs and thus the corners might not have received any of the chemical.

[togor]

Certainly not Mr. Beard, But I think the answer lies in the fact that the barrels ( and rear sight base ) were blued using the rust blue method and not in hot blue tanks. The bluing ( rusting chemical ) was applied with swabs and thus the corners might not have received any of the chemical.

That makes sense. Thank you!

[John Beard]

Absence of the bluing you see could have resulted from any number of factors. As 98src has pointed out, barrels with rear sight bases installed were rust blued. Normally, the bluing solution is brushed on with a swab or brush, however it could also been applied by immersion. As you pointed out, absence of the bluing could have resulted from the presence of oil or grease, failure to wipe the bluing solution in the subject area, or perhaps even an air bubble in the immersion tank.

J.B.

[RCS]

Here are some photos of my Rock Island s/n 64145 with RIA 3-07 barrel465944659546596

[togor]

RCS, your bluing pattern near the sight base looks different than the first photo, but generally along the lines of what Mr. Beard describes. Thank you to both of you for your replies.

[RCS]

It is not often discussed but the breech or feeding cone on the barrel is in the white, the trigger
has the bottom hole and numbers on the butt plate door465974659846599

[togor]

A cone in the white in a rust blue era seems easy to manage by not swabbing it there. I know that M1 barrels had a cap that covered the chamber end and threads when in the phosphate tank. Unclear to me if a M1903 barrel from the phosphate era should have a cone in the white or not. I suppose it would depend on what they use to plug the bore.

[Sunray]

I have a beard. That wear is far more likely to be the result of the stock rubbing on the metal than anything to do with the application of the original finish.

[rayg]

RCS, nice early 03 features, Ray