Blast Baffle Material

[Gunfixr]

There seems to be several different ideas about what material is best for the blast, or first baffle in the stack of any given suppressor. Of course, this changes with caliber, full auto desired or not, etc., but, in general, something tougher is generally desired.
For rimfires, and many centerfires, 304SS or 316SS will be chosen. For heavier centerfires, 17-4PH or maybe 15-5PH, or Inconel or Monel will be chosen.

Both 17-4PH and 15-5PH are purchased on the market in their annealed condition, which means they are not anywhere near their best level of performance.

From looking around at specs, all these materials are tough, some are plenty hard, most have very good corrosion resistance.

However, someone will put a 17-4PH baffle in front of steel baffles, or uncoated aluminum, so corrosion resistance isn't the reason.

It would seem the primary baffle takes a lot of heat, and a lot of wear, in abrasive particles hitting it at high speed, with heat.

There are much better materials for this application. materials with higher heat resistance and better wear resistance.

Why does nobody use them?

[Rich V]

Cost of material and difficulty in forming/machining?

We are seeing things like low carbon Stellite being used so that's progress. For one of my recent builds I used T-15 HSS http://www.simplytoolsteel.com/T-15-hig ... sheet.html "washers" as inserts in my internal brake. These were inset in a 17-4 SS housing and then high temp silver soldered. This was done to mitigate erosion and it has worked perfectly, no trace of wear or erosion. Since I don't plan on doing multiple mag dumps I'm not concerned with melting the silver solder (~1200 F).

[daPhoosa]

You might be confusing "best material" with "good enough material".
For most diy builders, the cost and difficulty of "best" are not worth it given the other "good enough" materials will probably last forever with their specific usage.
Considering 17-4 specifically, it is silly easy to machine. A simple 1hr at 900f heat treat results in a very durable product. It holds strength to above 600f. There's really very little not to like about it (unless you're mag dump Rambo).

[missilemantdi]

You might be confusing "best material" with "good enough material".

We as DIY'ers can't afford the "Best material", our builds would cost 10's of 1000's of dollars and would last several lifetimes.

I personally like to use Inconel HX or Hastelloy X (equivalent) for blast baffles, a little more expensive than SS but there's a reason that it is used in rocket engines and not SS. Heat resistance, oxidation resistance and mechanicals are better at extreme temps upwards of 2000F. Which most baffles only experience for milliseconds and the bulk material never reaches that temp.
A short rod can be purchased thru Mcmaster that will get enough for your rear cap and blast baffles. Large drawback is machin-dis-ability...But I did it so you can too.

[speed6]

The OP didn't mention 416 SS. It seems like it would be a good "good enough" choice for DIYers, given its ease of machining. I have machined a few parts out of 416 on my crappy benchtop mini-lathe and it cuts great. This is a martensite stainless with some sulfur added to aid machining...any reason this would not be a good choice for anything up to and including centerfire rifle cans?

[missilemantdi]

416 would likely be good enough for most people, but it isn't as resistant to the nasty gases coming out of the muzzle. it is good enough for Bartlein or Hart to make barrels out of (although shorter life expectancy than the suppressor)

[Gunfixr]

You might be confusing "best material" with "good enough material".
For most diy builders, the cost and difficulty of "best" are not worth it given the other "good enough" materials will probably last forever with their specific usage.
Considering 17-4 specifically, it is silly easy to machine. A simple 1hr at 900f heat treat results in a very durable product. It holds strength to above 600f. There's really very little not to like about it (unless you're mag dump Rambo).

That could easily have a lot to do with it, I guess.
Just reading around, I kept seeing things about using "so and so" material for the blast baffle, like it was special, but what was picked wasn't all that special.

But maybe it was special enough.

I'm betting most DIYers aren't heat treating any 17-4. The home oven isn't going to 900, maybe the propane torch. Mapp gas will get there, but maybe not on a part as large as a baffle, plus holding it in the flame for an hour. You can buy 4140 already hardened and tempered pretty cheap, and it'll be around Rockwell 33-35C, but I don't know about wear.

Of course, while factory centerfire suppressors are using either SS, or going Inconel, on rimfire, half the time the first baffle is just aluminum like the rest. A few use a SS or Ti first baffle. The baffles aren't even anodized, just bare aluminum.

Nitronic 60 SS isn't too expensive, a little tough on tooling, but not bad to machine. No worse than Ti. It has great wear resistance, even hot. Not real hard, similar to 304 SS, and similar corrosion resistance.
Seeing that, and it's price just got me wondering, I guess.

416 isn't going to be really any better with wear than 17-4, unless you heat treat it.

You know, if you had a way to get it good and hot, I guess the really cheap way out would be some regular mild steel and case harden it. It would have a real hard surface, 65C, but the core would be soft so it wouldn't shatter with the first shot. That would probably wear pretty slow. You could do it with a torch most likely, since it wouldn't take a lot of time, and a large cone could just have most of the nose done. You can even case harden 304 or 316 SS. The cased part would lose some corrosion resistance, but the rest would be unchanged.

[Samson104]

unless you are running a very short barrel or back to back mag dumps from a full auto the chances of you wearing out a 316L blast baffle to the point that it has a negative effect of the suppressor's performance is slim to none. Make your blast baffle .100"-.125" thick and put your mind at ease.
I've used 17-4 in a few builds and I honestly do not think its worth the little bit of added expense or hassle.

I've actually got a 308 can that has just over 900 rounds through it that is performing great and a bore scope shows very little wear at all a lot of which isn't really wear but just carbon , its based closely off of the AAC Cyclone desgine , a small 1.5" blast chamber with a 316L cone at .125" thick , followed by 2 more 316L .065" thick cones spaced .750" followed by 8 .065" 7075 aluminum cones spaced at .625" and .500" staggered. , suppression if fantastic on a 18" 308 running factory 175g ammo it has a different sound (deeper) that the 30 cal Thunderbeast , Crux and SAS cans i've compared it to and is just as quiet if not more so.

I think it last well past the life of the barrel before their is any noticeable change in suppression.

I honestly believe that most form-1 guys (who machine all parts) way over build their cans.

[tom_penn01]

17-4 can be purchased in h900 and h1150 from mcmaster-carr

http://www.mcmaster.com/#catalog/121/3774/=x6yelx

[Gunfixr]

Samson, I'm seeing what you mean. I built my multi-cal can entirely out of Ti, including the blast baffle. It runs on a 9mm SBR, a .308 with a 20" barrel most of the time, using full power loads, and several ARs, mostly a 16" barrel and a 10.5" pistol. It has a 2" blast chamber, because the 9mm is a locked breech operated by muzzle pressure pushing the barrel back, and while it's only got maybe 500 rds through it yet (I don't get much range time these days), there's no noticeable wear on the nose of the blast baffle.

I am thinking of moving it back further, but that's because the 9mm still runs too hard. Rotex makes a can for that gun, but I can't find pics of it's internals or specs, so I had to guess it's internal room.

I just made an all Ti rimfire can, so we will see how it holds up.

Yes, I realize that "07" is in my sig line, which means I can replace parts, but I don't own the place. There is no guarantee if/when I do need to replace something I will be able to. And, why would I want to?
If nothing else, you guys get to find out if Ti blast baffles hold up, without having to try it yourselves.

[BinaryAndy]

Just a few things to add here. 17-4 can be improved a lot by hardening it, no doubt, but it's still really quite strong and wear resistant even in the annealed condition. It really is dramatically better than 304 and 316. It has more than double the yield strength.

One failure mode of baffles that I don't see mentioned often is deformation of the material around the bore. As you put rounds through the can, the bore will slowly get smaller as the muzzle blast "peens" material from the face of the baffle in towards the bore. You need adequate hardness to resist peening. That's the only thing that would make me nervous about nitronic 60, since it's not that hard.