Topic: Suppressor Residue Analysis Advice Needed

[Brandon Bertolli]

I have a suppressor which I am testing to destruction or failure. It is an A-TEC CMM4(6) aluminium suppressor made in Norway. I am allowing residues to collect in the suppressor because I don't clean it at all, I don't even spray any oil in there. Here's where I am now, at 11000 rounds:





To me, the residues as seen radiologically look very dense and my current theory is that these residues are mostly lead. I've heard opinions to the effect that most of the residues by volume will be carbon deposits, not lead.


Eventually when this can fails I am going to take it apart carefully and collect all the residues, taking care to segregate them into 7 containers representing the 7 air spaces present in the suppressor. Then I want to send the residues for analysis. I want to know what's in the residues and whether they are distributed evenly in all the baffles or whether some elements such as lead will be more readily found in the first baffles, as a percentage.


I need some advice:


1) I am going to have to scrape the baffles to get all the residues out. What material is best for the little spatula and picks I will use? Is plastic okay or should I use a metal softer than the aluminium? I don't want to contaminate the residues because if aluminium is found in the residues it must have been eroded off the baffles. I need to know this.


2) What is the best analytical test for me to ask for, to get the information I need? I want to arrive at a point where I can say what the material profile is per container, preferably by weight. So for example if a container has residues totalling 7g, I would like to know how much of that is lead, how much is copper, how much is aluminium, how much is carbon-based propellant etc. I don't know how the wax from the rounds will figure in this, but if I could at least find out about the lead, copper and aluminium that would be great. I've been firing mainly lead rounds through this suppressor, but there were several thousand copper-washed CCI rounds also.


If you have any suggestions about which labs could do an analysis like this for a private individual, that would be great. I don't have any idea of the cost. If the cost is going to be prohibitive I may have to settle for a different test or nothing at all.


The suppressor is cheap enough but not the ammo. I typically spend around £480 per 5000 rounds so I have already fired £1000 through it and may end up firing another £500 before it fails!


(A failure is if it no longer suppresses sound properly, or accuracy suffers to the point that it can't used, or there is physical damage to the suppressor)

[Stacey Phetteplace]

I can't answer any of your questions, but this is a really cool idea!

[Greg Laskowski]

May I suggest that you use the sticky disks used for GSR testing by sampling (dabbing) the seven areas and submitting them to a lab that does GSR testing using these disks in an automated process.

[Brandon Bertolli]

Hi Greg


I am guessing that method will be the most cost effective. I have two concerns though:


1) I either have to supply multiple discs with all the residues dabbed, per area


or


2) I have to mix the residues and dab a representative sample, and only send a portion. In that case I only send 7 discs.


In case (1) I think I'm going to be sending in a lot of discs. In case (2) I might not get an accurate result if the dab doesn't contain a representative sample of the residues, which is also in the same elemental proportions.


How would I get around these problems?


Actually on a more basic level, what is the output of that GSR test? What I mean is, what information is output and how is it presented?

[Brandon Bertolli]

I can't answer any of your questions, but this is a really cool idea!

Thanks!
I've purchased another 10 suppressors to do similar tests on. I'm in the process of doing all the control imaging and this time I hope to do sound level tests also.

[Greg Laskowski]

Brandon,


I am supposing you would use one sticky disk per section and sample accordingly without overloading the adhesive on the sticky disk.  So, if you are sampling 7 baffles that might be 7 disks plus a blank and one for a positive control.  You would be analyzing via SEM EDX.  This process allows you to get an elemental analysis.  This would be quantitative in nature.  For those labs that do automated GSR analysis, they would be looking at lead, antimony, and barium, but they could also report, copper, aluminum, zinc and anything else associated with ammunition.  SEM/EDX will give you an image of the particle analyzed and its elemental composition.  Not only that the but the elemental constituencies on the disks can be mapped as well.If you swab, then you might try Inductive Coupled Plasma Mass spectrometry.  This is a very sensitive technique and might see some of the lighter metals that you might not see with EDX.  Swabs are cheaper than disks but you would hope that the reagent you use to solubilize the debris, most likely aqua regia will be able to get the desired elements into solution.


Good luck with your project.

[Brandon Bertolli]

Thanks Greg


I will read up on those two tests (I know next to diddly about those and I don't want to waste your time asking more questions without knowing the basics).

[Justine Kreso]

I was going to suggest the same as Greg. 

[Aaron Brudenell]

You may contact Phil Dater of Gemtech, he's also an AFTE TA.  I suspect his input will be useful.