Great thread and great info. Definitely worth a sticky.
Great thread and great info. Definitely worth a sticky.
Excellent info. I work with automotive engine components, and we get virtually identical material certs for the different steels and nickel alloys we use, and have to provide nearly identical testing certs for our completed components as well.
Grant,
Do you happen to know the spec on the bore/chamber chrome plating thickness?
Thanks for the education. Great write-up.
Thanks Grant, well worth the read.
"This is 2012. The world is going to end this December and people are still trying to debate the merits of piece of shit, cost cutting crap AR's. Really?"-Iraqgunz
"You live more in 5 minutes on a bike like this going flat out than some people live in their lifetime." - B. Munro
Last edited by C4IGrant; 06-15-10 at 09:55.
Grant, I would be very interested if you can get it. In my current job, I design engine valves, which have a far more similar function to a rifle barrel than most people realize, and often in a far more harsh environment. Many of my valves are chrome plated on the stem for both wear resistance, and in some cases to improve corrosion resistance. I typically spec chrome plate in the 9-14 micron thick range, and I'm wondering how comparable it is to "mil-spec" on a chamber/bore. I'm also assuming the spec is the same for thickness in the chamber and bore, but it wouldn't necessarily have to be.
One other thing I wouldn't mind pointing out as a corollary to the original post, is that just because something isn't "mil-spec" doesn't mean that it is automatically junk. A newer, and better steel that wasn't around when the spec was written wouldn't be mil-spec, but by definition would be better. A process like nitriding wouldn't be mil-spec on a barrel, but could provide a more consistant and better wear and corrosion resistant surface for the barrel than mil-spec (depending on the steel used). I guess my point is, we shouldn't use mil-spec as a crutch so much, and evaluate each individual component design and build quality for its intended use, especially when our usage of the item is not the same as what drove the creation of that mil-spec in the first place.
Last edited by Rara; 06-15-10 at 13:14.
Thanks, and I couldn't agree more. The difficulty is often the lack of available technical information, and/or relevant testing. It frustrates me to no end how many people have no concept of good objective testing, and fall back to the "well, my Uncle Nester had one, back in aught-four, and he dropped three squirrels with one shot, so it must be the most amazing thing ever" type anecdotal stories.
but to be fair, the mil-spec is written to be the minimum acceptable, and cost and high volume manufacturing considerations are a huge part of the decision making process in developing the specs. As an example, I can think of a half-dozen different stainless steels I use daily that would perform far better in every way than a 4150 CMV in an AR barrel, but they would be awfully hard to make in high volume, and not to mention expensive.
the mil-spec is written to be the minimum acceptable, and cost and high volume manufacturing considerations are a huge part of the decision making process
This is correct. ^^^^^^
These weapons and parts ase made by SEVERAL different companies. Mil-Spec establishes a minimum acceptable standard so all manufactured parts fit no matter where they came from.
just because something isn't "mil-spec" does not mean it is junk.
This is true as well ^^^^
Materials and methods have come along ways in the last 40 years.
Last edited by Failure2Stop; 09-09-10 at 20:14.
Rara, you may find this interesting. It is from an interview with John Noveske where he is discussing his barrels:
Crane: Right, o.k., now you’re double-chrome-lining your barrels, or some of your barrels, not the stainless steel barrels, but the…
Noveske: The N4 Light Carbine and N4 Light Recce barrels.
Crane: Light Carbine barrels. You’re double chromin’ ‘em, and obviously, you must be getting a pretty nice even chrome job on there.
Noveske: Yes. I have a tolerance that is equal to a match-grade barrel.
Crane: Equal to a stainless barrel?
Noveske: Well, that doesn’t mean anything, because there’s a lot of different makers of stainless barrels, but there is a kind of an unspoken match-grade tolerance in the custom barrel world of 2/10ths of a thousoundth concentricity, or…in uniformity of bore diameter from end to end, and I spec that out on my chrome-lined barrels.
Crane: Are you the only guy that’s double-chrome-lining ‘em?
Noveske: That’s not the right [terminology]. "Double-chrome-lining" implies that I’m chroming twice. I’m chroming once to the technical data package requirements for the M249 machine gun [FN M249 Squad Automatic Weapon a.k.a. FN M249 SAW], which call out for a chrome thickness that is approximately twice the thickness of an M16 or an M4.
Crane: The barrels that we’re talkin’ about are Pac-Nor.
Noveske: Our stainless barrels are made partially in ourshop and partially in Pac-Nor’s shop. And, the relationship that I have with Pac-Nor…I used to work there, and now what’s goin’ on is I buy steel, I take it to Pac-Nor, when the guys clock out of Pac-Nor, they clock into our barrel production. They machine my blanks with our tooling, which is all made to our design, including the drills, reamers, button, so forth, so on. They stress-relieve to our recipe, and then they give the barrels back to us, and then we finish them all in our shop.
Crane: What type of stainless are they using?
Noveske: Well, they use 416 project 70. I use a different type of material.
Crane: And what about the standard steel barrels? What kind of steel is that?
Noveske: Let me back up. You can’t call the barrel that we make a Pac-Nor barrel, because if you call Pac-Nor and order a stainless barrel, it’s gonna’ be much different. It’s gonna’ be different in every way from the barrel I sell. So when you say "what kind of materal do they use?", last time I checked, Pac-Nor uses 416 project 70 made by Carpenter, and I use a different material which is technically considered 416R, and it’s a lot harder than any stainless we’ve ever tested from other manufacturers. Our stainless comes in around 32 on the Rockwell C scale, and that’s harder even than the call-out for the M16 barrel.
Crane: And the standard barrel that’s being chrome-lined, the non-stainless-steel barrel, what kind of steel is that?
Noveske: That’s the same steel that’s in the technical data package requirement for the M249.
Crane: And what is that?
Noveske: Well, I’m not gonna’ talk about what it is, specfiically.
http://www.defensereview.com/noveske...view-part-one/
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