Cone and Spacer Material: Beware of False Advertising

[Bee]

Purchased two 60 degree cones, one 2” spacer and one 1” spacer from a well known vendor. The cones and spacers were advertised as 17-4 PH. When I received the cones and spacers, they appeared to be 300 SS. Out of curiosity, I tested them to confirm composition. I mean, how would/could a vendor sell 17-4 and ship me something else ??

Tests performed were: a) Magnetic and, b) XRF. Magnetic induction was the initial test to used sort ferromagnetic materials such as carbon steel and ferritic stainless steel ( such as 17-4 PH) from paramagnetic materials such as 300 series SS. If material fails the magnetic test (in this case, if it is paramagnetic, it cannot be 17-4 PH), then X-Ray Fluorescence (XRF) test was employed to determine Ni and Cr content.

Results: Cones and spacers were paramagnetic, XRF showed Ni/Cr composition consistent with 304 SS. Thus, tests confirm vendor is sold me 304 SS in lieu of his advertised 17-4 PH. As an aside, vendor does not list 304 SS as an option for any of his cones or spacers

I am not publishing vendor name as I have contacted him and waiting on response. Have offered to send back the 304 SS cones and spacers for a refund or replacement with 17-4 PH material.

For the lay person: If you order 17-4 components, and if a magnet does not stick to it, you probably have 300 SS.

Yes, I am a Metallurgical Engineer.

[ECCO Machine]

That sucks, but I've seen it before. I've had a number of cones sent to me for clipping, and in more than one case they were some flavor of 300 series (I don't have XRF to further narrow it).

[Bee]

Humm...seems I am just another sucker in the fake cone material scam.

My post is primarily a public service announcement. My intent is to expose fraud and keep scammers from ripping off honest folks.

Anyone buying cones or spacers advertised as 17-4 PH should test with a magnet upon receipt. At the very least, you will know if you have a 300 series SS or some type of ferritic SS. At least you can Q&T 400 SS and get some decent properties; with 300 series you cannot do any beneficial heat treatment.

I actually have an email from the vendor confirming that his advertised SS spacers are actually 17-4 PH (prior to my purchase). I may post our exchange just to prove my point. The nerve ..... If he simply had tested his own materials with a magnet—and maybe he did— he would have known it was an austenitic material and not 17-4 or 400 series SS.

Unfortunately, the vendor is mentioned in several threads with no bad reports...until now.

Luckily I have access to high end equipment for chemistry and other material testing. The XRF analysis is non destructive only takes 5 seconds to get an assay level analysis of elements. I may post photograph the XRF results on his cones and spacers in a later post. Maybe he will start advertising the truth.

[ECCO Machine]

The thing I'd be most curious to learn is the why. It's not like 17-4 is hard to come by or expensive. My cost on 17-4 round bar is about the same as most 300 and 400 series alloys. I'd also much rather machine 17-4 than 304.

I do often use 304 or 316 tube for longer blast chamber spacers to keep cost down on a part where the strength and hardness of 17-4 H900 simply isn't necessary. But I can't think of a reason one would use 300 series for the cones.

At least you can Q&T 400 SS and get some decent properties; with 300 series you cannot do any beneficial heat treatment.

I dare say much better than decent with the right alloys. I have used 440c with a 550° temper in .338 Lapua builds, which will never see extreme temperatures but which benefit from the erosion resistance of the much harder material. I also sometimes build with 422 tempered to 980° for more severe duty uses due to it's having superior hardness and strength to 17-4, especially at elevated temperatures. But 17-4 is my go to for the extreme majority of parts due to the ease of achieving high surface finish quality, the simple heat treatment and it's excellent dimensional stability with tempering while still having high mechanical properties. I wish it got harder than it does, but 40 Rc isn't terrible.

[Rich V]

Snip
But 17-4 is my go to for the extreme majority of parts due to the ease of achieving high surface finish quality, the simple heat treatment and it's excellent dimensional stability with tempering while still having high mechanical properties. I wish it got harder than it does, but 40 Rc isn't terrible.

I have the solution you seek. 300c maraging steel.
Too bad the stuff is so damn expensive.

[ECCO Machine]

I have the solution you seek. 300c maraging steel.
Too bad the stuff is so damn expensive.

422 has mechanical properties just barely below 300c with better corrosion resistance and lower material cost. That's why I use it. 422 is stronger at 900°F than 17-4 H900 at room temp.

[Matt in TN]

Wow - good information, thanks! Especially the part about a simple magnet test.

All I've seen in the past to tell dofferent steels apart is to grind them and see what color the sparks are. That's pretty subjective and has been tough for me to learn on my own.

[#40Fan]

Well, come on now.

Gotta tell us who it is.

If it is a well known vendor, I bet I can post up a question on the Form 1 board and have an answer if you don't want to share.

Edit: Since I have a bunch of cones from various suppliers and you mentioning SS spacer material, it narrowed it down pretty quickly.

Muted machine works cones that I have are non-magnetic.

[Bee]

Wanted to give vendor a chance to reply and do the right thing. Seems their approach is to ignore email I sent explaining, in detail, the actual metallurgy of their advertised 17-4PH skirtless cones and “17-4 PH” spacers.

Recall in my previous post that I emailed them about their SS spacers, asking what type of SS they were selling, and was told they were 17-4 PH.

As ECCO explained, it should not be a cost issue with 17-4. My best guess is that 304 SS is what they had, so they peddled it as 17-4 PH. Motivations are hard to discern; but why one would risk reputation in the relatively small Form 1 world is odd.

Full disclosure: I am a newby in the Form 1 arena. Thus, I have no in-depth experience or first hand knowledge with material performance in the unique suppressor environment. However, there are direct correlations to CRA performance in my area of expertise, so it’s immediately obvious when folks have a clue. From several posts I have read, it is obvious that there are some pretty knowledgeable people on this board.

There are several materials that would serve great for suppressor baffles , but it seems to me that the industry has generally settled on reasonable compromises. The commercial market is very cost competitive and very, very few of us run 10 inch .233 ARs on full auto. Thus, for typical Form 1 builders shooting center fire supersonic ammo, 17-4 and Ti are IMHO the best options,

BTW: Yup, it was muted Machine Works...

[Bee]

I have the solution you seek. 300c maraging steel.
Too bad the stuff is so damn expensive.

422 has mechanical properties just barely below 300c with better corrosion resistance and lower material cost. That's why I use it. 422 is stronger at 900°F than 17-4 H900 at room temp.

ECCO,
Indeed...my prior reference to 17-4 and Ti was pointed to those of us who are stuck buying ready made parts...in this apparently sketchy market. In defense of some Form 1 solvent trap vendors, one was open and honest with me. Even offered to sent material certs.

[ECCO Machine]

There are several materials that would serve great for suppressor baffles , but it seems to me that the industry has generally settled on reasonable compromises. The commercial market is very cost competitive and very, very few of us run 10 inch .233 ARs on full auto. Thus, for typical Form 1 builders shooting center fire supersonic ammo, 17-4 and Ti are IMHO the best options,

17-4 will actually hold up quite well on short barreled machine guns, too, provided you don't do back-to-back mag dumps.

This is my 100% 17-4 Five By Five model on a 7.5" M16

https://www.youtube.com/watch?v=2YmqmqT1E0k

I haven't kept track of the round count on this one, but it's been hot enough to burn the moly resin off before (>1,000°F). This can has been used exclusively on a 10.3 barreled M16, mostly firing full auto. Yes, that's copper from bullet jackets stuck all over the inside of the blast chamber

[Bee]

That is informative. Theory and opinions aside, test data trumps all else. We have models for erosion with empirical inputs, but parameter limitations do not encompass the velocity, temperature and high velocity particle angularity/hardness encountered in suppressors . Thank you for the education.
With my intended use (hog hunting) it seems to me a 17-4 blast baffle with remaining baffles in Ti is more than sufficient.
Too old to be fascinated with mag dumps and too lazy to do three gun.

[SILENCERSTUDENT]

cats out the bag now

[0101silent]

Is there any chance that the cones are made from 303 Stainless?

Purchased two 60 degree cones, one 2” spacer and one 1” spacer from a well known vendor. The cones and spacers were advertised as 17-4 PH. When I received the cones and spacers, they appeared to be 300 SS. Out of curiosity, I tested them to confirm composition. I mean, how would/could a vendor sell 17-4 and ship me something else ??

Tests performed were: a) Magnetic and, b) XRF. Magnetic induction was the initial test to used sort ferromagnetic materials such as carbon steel and ferritic stainless steel ( such as 17-4 PH) from paramagnetic materials such as 300 series SS. If material fails the magnetic test (in this case, if it is paramagnetic, it cannot be 17-4 PH), then X-Ray Fluorescence (XRF) test was employed to determine Ni and Cr content.

Results: Cones and spacers were paramagnetic, XRF showed Ni/Cr composition consistent with 304 SS. Thus, tests confirm vendor is sold me 304 SS in lieu of his advertised 17-4 PH. As an aside, vendor does not list 304 SS as an option for any of his cones or spacers

I am not publishing vendor name as I have contacted him and waiting on response. Have offered to send back the 304 SS cones and spacers for a refund or replacement with 17-4 PH material.

For the lay person: If you order 17-4 components, and if a magnet does not stick to it, you probably have 300 SS.

Yes, I am a Metallurgical Engineer.

[ECCO Machine]

Is there any chance that the cones are made from 303 Stainless?

Purchased two 60 degree cones, one 2” spacer and one 1” spacer from a well known vendor. The cones and spacers were advertised as 17-4 PH. When I received the cones and spacers, they appeared to be 300 SS. Out of curiosity, I tested them to confirm composition. I mean, how would/could a vendor sell 17-4 and ship me something else ??

Tests performed were: a) Magnetic and, b) XRF. Magnetic induction was the initial test to used sort ferromagnetic materials such as carbon steel and ferritic stainless steel ( such as 17-4 PH) from paramagnetic materials such as 300 series SS. If material fails the magnetic test (in this case, if it is paramagnetic, it cannot be 17-4 PH), then X-Ray Fluorescence (XRF) test was employed to determine Ni and Cr content.

Results: Cones and spacers were paramagnetic, XRF showed Ni/Cr composition consistent with 304 SS. Thus, tests confirm vendor is sold me 304 SS in lieu of his advertised 17-4 PH. As an aside, vendor does not list 304 SS as an option for any of his cones or spacers

I am not publishing vendor name as I have contacted him and waiting on response. Have offered to send back the 304 SS cones and spacers for a refund or replacement with 17-4 PH material.

For the lay person: If you order 17-4 components, and if a magnet does not stick to it, you probably have 300 SS.

Yes, I am a Metallurgical Engineer.

I think his XRF would identify the sulphur content, and being a metallurgical engineer, he'd know what it means.

Wouldn't matter anyway, though. 303 is just a free machining grade with basically the same mechanical properties as 304. 316L would be an improvement, but still way below even tempered 416, let alone 200 KSI 17-4 H900.

[Bee]

The analyzer did not have light element detection capability (detection range of the analyzer: Ti -U), thus S was not measured. Was not interested in the exact 300 SS grade and did not bother with light element analysis with a higher end analyzer.

[#40Fan]

On the form 1 board there was a question on whether the Ti was a grade 5 or not. Do you have the capability to test it? Do you have any MMW Ti cones?

[Bee]

I sent a long response but it seems to have vanished into the internet either. Maybe it will eventually find its way, but in the mean time:
I plan to test Ti cups and spacers when I return to the USA. Test will be for vanadium content, the distinguishing element between Grade 5 and 9.
This is my last post on this issue. I have achieved my intended objective.

[#40Fan]

Well, thanks for the information that helped us all learn the truth about the products being sold by MMW.

Not sure if you browse the form1 board, but one member posted an email response from MMW that said the cones were in fact 17-4, but were a low "magnetic" grade. His own lab testing results.

If you do get the chance to test the Ti, myself and I'm sure MANY others would like to hear the results. Please post them if you would.

Again, thanks for the information you provided.

[Bee]

No such thing as low magnetic 17-4...unless you use a very low gauss magnetic from your refrigerator.

[Matt in TN]

So I finally got around to testing some of my stock. The good news is that everything I have marked 17-4 is magnetic. And everything I have marked 316 or 3xx is nonmagnetic.

But the 416 is also magnetic.

Any other tips for how a layperson can tell all these apart?

[Bee]

A few views to consider:
You cannot read too much into testing with a magnet. The way you are using it, it’s a sorting tool to discern martensitic or ferritic stainless steel from austenitic stainless steels. You are not going to be able to determine or divine anything more specific.

Just for some clarity, if you had, say 17-7 PH or 2205 duplex stainless steel (with dual austenitic/ferrite SS phases), you would see moderate/weak magnetic attraction.

For the average guy without access to lab grade test equipment, IMHO, defining the exact grade is not possible. The best I can tell, your best option is quiz the vendor on how he verifies material composition, how he procures and where is the material supply source ( not where it is machined, but the source of the metal) . Beware of “Made in the USA” advertising—it does nit mean the material is USA sourced. Unless the part is machined and material is sourced in the USA, you can be fooled with the Made in the USA logo.

Super Precision Concepts is one vendor who seemed legit (may be others but I have only traded emails with 3-4), was open with his response to these question and seemed knowledgable (I have no connection to nor endorse SPC).

[Bee]

So I finally got around to testing some of my stock. The good news is that everything I have marked 17-4 is magnetic. And everything I have marked 316 or 3xx is nonmagnetic.

But the 416 is also magnetic.

Any other tips for how a layperson can tell all these apart?

Forgot to mention:
Your “416” should be magnetic. 416 is martensitic (with intentional sulfur addition for Machine ability).

[Matt in TN]

Good stuff - thanks for taking the time to post!

[Bee]

On the form 1 board there was a question on whether the Ti was a grade 5 or not. Do you have the capability to test it? Do you have any MMW Ti cones?

Tested one each of MMW Ti cup and spacer. Both advertised as Gr5 Ti. Short summary:

Cup was G2G.

Spacer, not as advertised Gr 5 Ti:
- Odd chemistry, at least to me. With vanadium around 1%, it was not Gr5 or 9, and not Gr 1 or 2.