Standard thickness of chrome lining?

[WAR FACE]

What is the standard thickness of chrome lining in barrels?

[Seth247]

Not an answer but a related question....

I've always wondered how chrome lining effects chamber and rifling dimensions. Do manufacturers cut the bores and chambers a little looser on barrels to be chrome lined? Or is the lining so thin that the increase in clearances is negligible?

Also, what about the FN CHF barrels everyone's been selling lately that have "double thick chrome lining"?

Sorry about small hijack.

[nimdabew]

Chrome lining has been around a long time and is very repeatable and measurable. Bores and chambers are overbored enough to account for chrome thickness.

[kartoffel]

From Electrohio.com, http://www.electrohio.com/Finishing/Chrome/HardChrome.htm

The standard thickness for Hard Chrome plating in nonsalvage applications is .0002 - .0006”

From nmfrc.org, http://www.nmfrc.org/crarchive/sep07a.cfm

Q. What's the maximum thickness of hard chrome plating that can be deposited on ferrous metal after which the layer starts disintegrating?

Is there any measure of adhesion which can be checked, if so, the method to check?

A. If properly applied, there is no set limit to the thickness of hard chrome, but as a general rule, chromium is most stable on ferrous alloys in the range of 0.0005 to about 0.025 in a single application. Chromium deposits over 0.025 per side can begin to become rough with build up at edges and pitting. Success with thick chromium deposits has a lot to do with the initial surface finish of the base metal.

When applicable, "after plate finish requirements", i.e., uniformity, mimimum thickness, surface micro finish and micro-crack acceptance level, dictate the best chromium procedure to follow. The initial set up, tooling and especially anoding procedures, are critical steps to achieving the most success.

Chromium deposits can be applied in numerous ways, with a variety of results to achieve specific customer requirements. One such procedure is to apply a layer of chromium over top a layer of nickel, when coating thickness requirements exceed 0.025 (per side).

As for what the "standard" thickness is in gun barrels, I couldn't tell ya.

[Seth247]

That makes sense. About half a thousandth sounds right.

[WAR FACE]

Damn I was thinking around .005 that is thinner than I would have thought. Thanks for the info!

[apb2772]

Chrome lining has been around a long time and is very repeatable and measurable. Bores and chambers are overbored enough to account for chrome thickness.


NO.

This is a common misconception. The plating is thin enough that the reamers, buttons and or other bore shaping equipment are all the same for any given bore diameter - chrome lined or not.

Chrome lining is NOT like paint or other surface coatings.

--->APB