DD CHF Barrels - nitride exterior and still chrome-lined bore?

[SomeOtherGuy]

Sometime in the last year or so Daniel Defense adopted salt bath nitriding for something relating to their barrels. Looking at the 18" S2W barrel linked below, the DD website indicates that the exterior finish is nitride treatment while the bore is apparently chrome lined. Is that correct? I'm asking just because other manufacturers that adopted nitride treatment for anything used it both inside and out, and I thought I read somewhere that these barrels were purely nitride treated, no longer chrome lined.

https://danieldefense.com/cold-hammer-forged-barrels/18-inch-chf-barrels/18-5-56mm-s2w-mid-length-chf-barrel-stripped.html

Thanks in advance.

[mallbritton]

The bore of the 18" S2W® Barrel is Salt Bath Nitride. The material is Chrome Moly Vanadium Steel. You are correct, it is not chrome lined like the phosphate barrels.

[WS6]

I am a huge fan of QPQ, as the layer extends into the steel deeper than a chrome-lining layer is thick, and is tougher to boot. However, has any quantitative testing been done to show an effect on bore life?

Also, how do these bores look? Are they matte, or shiny and smooth? I had a SIG barrel QPQ'ed, and it copper fouls worse than before, and is matte in color/"texture", while my factory Glock barrel looks like a mirror. I have a suspicion that my SIG barrel was not polished after the final quench, and am curious from someone who owns one...is the DD barrel interior a mirror, or matte, in finish inside? To quantify, Chrome is somewhere between the two, regarding how the "texture looks", to me.

[MarkG]

I guess you could plug the bore and drill the gas port post dip but typically nitriding is an all or nothing process. So the question is, can a bore that has been nitirded also be chrome lined?


I am a huge fan of QPQ, as the layer extends into the steel deeper than a chrome-lining layer is thick, and is tougher to boot. However, has any quantitative testing been done to show an effect on bore life?

When making a comparison (nitriding v. chrome), the depth the treatment extends into the metal is irrelevant as long as they are the same. An unserviceable bore is an unservicable bore.


Also, how do these bores look? Are they matte, or shiny and smooth? I had a SIG barrel QPQ'ed, and it copper fouls worse than before, and is matte in color/"texture", while my factory Glock barrel looks like a mirror. I have a suspicion that my SIG barrel was not polished after the final quench, and am curious from someone who owns one...is the DD barrel interior a mirror, or matte, in finish inside? To quantify, Chrome is somewhere between the two, regarding how the "texture looks", to me.

The "P" in QPQ is key. It is much easier (read cost effective) to polish a larger diameter pistol barrel that is less than 6 inches in length than a 16 inch rifle barrel that is slightly larger than two tenths of an inch.

I agree that QPQ and its many variants are something to consider for certain applications. The JP bolt carrier and Glock barrel are a couple of great examples. Lacking a lot of reliable data, I'm just not sure that a rifle barrel is a good candidate for nitriding.

Two of the big drawbacks to nitriding, unlike chroming a bore, is that it is a batch process and there is no standard recipe. Screw up the chroming process and you have only lost one barrel. Screw up the nitriding process and you just scrapped dozens of barrels.