Is a blast chamber really needed/heat treating baffles

[Hannibalbarca]

how necessary is needed to have a main blast chamber in a suppressor.
say the suppressor is all stainless steel with the tube having a wall thickness of .075 inches and the baffles being 17-4 stainless steel(60 degree cone cups and clipped) and .065 inche thick with the skirt being .669 inches long.
would a blast chamber be needed?
say the caliber being fired is 308 winchester using some hot loads, maybe even 300 winmag.
if you had to guess would this lower the life expectancy of the first baffle? im guessing yes but my question is by how much and how would it fail eventually?
Would heat treating the baffles(17-4 ss) be a good idea? Should I just heat treat the first one or could I heat treat all of them? The hardness increases but so does the brittleness which is my concern.
What about a melonite treatment of the whole suppressor?

if i do need one how long should it be? is 1 inch fine?

[garredondojr]

i'm still learning but yes a blast chamber is necessary. you need a certain amount of volume to allow the gasses to expand as they leave the barrel. the amount of powder being burned and barrel length play a important role.

the smaller the chamber and the larger the powder volume the more pressure will be exerted inside the suppressor. this could bulge/split the suppressor and you would also have less time for the gasses to cool which would cause alot of errosion to the baffles.

[Hannibalbarca]

i'm still learning but yes a blast chamber is necessary. you need a certain amount of volume to allow the gasses to expand as they leave the barrel. the amount of powder being burned and barrel length play a important role.

the smaller the chamber and the larger the powder volume the more pressure will be exerted inside the suppressor. this could bulge/split the suppressor and you would also have less time for the gasses to cool which would cause alot of errosion to the baffles.

Would 1 inch or 1.5 inches for a spacer work well then?
What do you think about my idea of heat treating the baffles and adding a melonite coat?

[garredondojr]

If you seriously want to run a 300 win mag I would go no less than 2" one way you can sort of cheat this would be to do something like I'm planning.

my suppressor will be setup for the griffin taper mount I too want 300wm as a capability so in that case I would run a direct thread adapter (or minimalist single port brake) which will maximize the blast chamber volume.

for my .308 and .260 I will run brakes so some of the chamber will be displaced by the brake.

for my 5.56 guns I'm going to run over the barrel mount's which will further use chamber volume and making it the shortest as possible.

as for heat treating and melonite if you have the means to do it correctly then by all means it's nothing but pro's. you'll get higher strength an erosion resistance with the HT and the melonite will help further with erosion reisistance as well as corrosion and may clean up easier?

if you don't have the hookup on those services from what I've read is you can purchase 17-4 already heat treated and certain grades will still machine decently (which one's slip my mind) then you can machine it and forget it at that point. 17-4 already has decent hardness and corrosion capabilities in pre hard forms. seem to recall you want to stay away from annealed as it can get be a bear to machine and gets gummy?

[3strucking]

17-4 ph.

[garredondojr]

17-4 ph.

but what level of ph? there's H900-1150

[cdakers]

17-4 ph is what you want to buy - it is still freely machinable. Then heat treat to H900 - 900* for 1 hour, then air cooled to room temp.

[T-Rex]

17-4 is not free machining. At best, H1150 rates at a 50. Cutting the annealed condition is less than optimal and H900 is worse. While less hard as annealed or H900, H1150 cuts decent and will do a fine job being internals. It will have corrosion resistance equal to 304, but have twice the UTS.

[Hannibalbarca]

17-4 is not free machining. At best, H1150 rates at a 50. Cutting the annealed condition is less than optimal and H900 is worse. While less hard as annealed or H900, H1150 cuts decent and will do a fine job being internals. It will have corrosion resistance equal to 304, but have twice the UTS.

I don't know the grade of the steel.
Does hardening the steel really increase the lifespan and durability? It seems like hardening it with heat treatment would make it more brittle and more prone to fissuring.

I definitely want to do melonite, but heat treatment I'm unsure of because of higher brittleness and also deformation of the metal.

[yondering]

17-4 is not free machining. At best, H1150 rates at a 50. Cutting the annealed condition is less than optimal and H900 is worse. While less hard as annealed or H900, H1150 cuts decent and will do a fine job being internals. It will have corrosion resistance equal to 304, but have twice the UTS.

I always wonder what people are doing who don't like working with 17-4. It's not "free machining", but most stainless isn't, and 17-4 still cuts beautifully if you manage the chips. It's one of my favorite materials to work with; easy to get satin smooth finishes, easy heat treat, high strength, good corrosion resistance, etc, and it cuts easily enough that taking off very light passes like .001" is no problem.

I make all my stainless muzzle devices from it now, and of course suppressor baffles when I'm building one.

I do all my turning with carbide though, and most of my milling as well. Maybe that's the difference.

[T-Rex]

I'm not trying to crap on 17-4. I just wanted to put actual material properties out there. I would much rather use 17-4, and I do, over 316 and, if weight is not critical, before Ti. If some on here have no ability to HT, and they want an easier machining state, H1150 would do the job. You can use it, for suppressor parts, in the annealed condition. However, I do not like cutting it in this condition.

Unless you subject it to severely adverse environments, 17-4 will hold the majority of its strength and resilience. Afterall, I doubt your going to get it to 1400*F and dunk it into seawater

[fishman]

No it cuts fine with high speed steel too.

Another one that people freak out about is grade 5 titanium. Ti 6al v4. It dulls hss tooling relatively quickly, but it's still easy to cut, just sharpen your tools often or use carbide or diamond and it's entirely a non issue.

[yondering]

T-Rex, gotcha. You are correct of course that 17-4 is more free machining in the hardened states.

I really like 17-4 partly for it's strength. In a F1 can I built several years ago, I'm using .030" thick cone baffles in 17-4 (blast baffle is .060" thick) for everything up to and including 306, 6.5 Creedmoor, and 35 Whelen, along with AR pistol/SBR barrels in several different calibers. No signs of damage or even significant wear at this point.

fishman - yeah I've noticed that with grade 5 Ti too. With Ti, it's heat that kills HSS tools quick, and apparently some just don't realize how fast it heats up. If you keep it cool or just use sharp carbide, it cuts really easily, no issues at all.