Suppressors Research I have done for my first form 1 can.

[TGagnon]

So I have been spending my weeks out here in the connex researching suppressors and how I plan on building my first reflex design form 1. This is for all my target guns up to 7WSM pressure and capacity.

I have researched materials via links below.
http://www.silencertalk.com/forum/viewtopic.php?f=10&t=85678
Followed the links on the first response.
Also looked at KAC AAC AWC SAS and several others to see if they list what they use.
I went and looked at the alloy that suppressor manufacturers list as what they use for their inconel blast baffles.
However there are different grades of inconel relating to its hardness and how it was treated before machining. The one common alloy that is listed on most suppressor sights is 718 but there is also different harnesses of that alloy.

I have 303 stainless tubing and bar and quantity enough to also do some practice first to see how they weld and machine.
My friend lets me run his mill and lathe, both manual, with his guidance. Have access to TIG and lots of practice doing tig and tons of practice with stick, should I choose to weld baffle stack into my main tube.

The plan is a suppressor with an over all length of 14 inch at 1.5 inch diameter. It will have a shoulder and thread on the rear end cap that will tighten down at the rear of a one piece long mount similar to the elite iron mounts but elongated. The end of the one piece brake assembly will be a modified vias style brake with a 1 degree taper on it for the first quarter inch that will mate up to the matching taper on the inside bearing surface of a support ring 6-8 inches inside the can.

The can will have a main tube and blast spacers that get thinner towards the front of the can to reduce some weight.

I plan on leaving the space between the rear endcap and my support baffle/ring empty. Yes it will make it harder to mount the can to the firearm than if I had a tube, but I don't ever intend to have to remove this can from the firearm and reinstall under any kind of pressure.

The ring will be one of three pieces I would like to make out of inconel. It will be a support ring primarily with 6 spokes supporting it from the wall to the center bearing surface for the end of my break. It will be .250 inch thick and the six supports will be machined either as straight bars as if on a pulley wheel or at an angle similar to a prop on an aircraft in order to cause more disruption on passing gasses. This would also be the most complex piece to machine if I went with angled spokes.

Second piece that I would like to make from inconel will be the blast sleeve/spacer that sits between the rear endcap and the back side of the support ring for the break. this will be to take the blast coming from my modified vias style 360 degree brake.

Third piece would be the first baffle, my blast baffle if you don't count the break itself.

I have also considered doing the spacer between the support ring and blast baffle of inconel as I will already ordering the material and adding 2 inches to material wouldn't cost to much.

The break assembly is going to be machined from a piece of stainless barrel from a burnt out 220swift straight 1.5 inch barrel I have laying around. I would like to send the brake off to get nitrided for the same supposed reason people like to nitride their barrels. I don't have personal experience with nitriding but was already planning on sending another barrel I have awaiting my work to finish it at home. After doing that much machine work should I send off the break to be stress relieved so that it doesn't warp during nitriding?

I plan on using stepped baffles similar to a recent 300 win mag can that was posted to silencer talk. http://www.silencertalk.com/forum/viewtopic.php?f=10&t=78425
Number of baffles has yet to be determined as I am still refining how I would like to do my mount system and I still havn't even started doing research into baffle spacing for best effect. Until I can get in contact with the gentleman that built the stepped baffles on that 300winmag can I will refrain from any kind of design refinements on my baffle stack as I really like how his came out.

Any help or critique would be appreciated and yes I know there is a lot of people on silencer talk that can help me but I am still working on a proper email account they will accept.

My big questions are what hardness treatment of 718 inconel, machining advice for inconel, were to get small quantity of this material, and baffle spacing.

 

[Wicked Weapons]

Re: Research I have done for my first form 1 can.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TGagnon</div><div class="ubbcode-body">I have 303 stainless tubing and bar and quantity enough to also do some practice first to see how they weld and machine.</div></div>
Your 303 SS will machine wonderfully; and weld like a molten pile of dog crap.

303 stainless steel is the most readily machineable of all the austenitic grades of stainless steel. The machineable nature of Grade 303 stainless steel is due to the addition of sulphur in the steels composition. The sulphur improves machining, but it also causes a decrease in the corrosion resistance and a slight lowering of the toughness.

Welding 303 SS is not recommended, although welding can be performed if low temperatures are employed. Recommended filler metal is AWS E/ER312. At high temperature, the sulfur in 303 tends to precipitate at the weld boundary resulting in weak and brittle joints. It's essentially unweldable for your purposes.

End result, use 304 SS where welding will be required. And even if it's not. It will make machining more difficult, but the welded joints will be MUCH stronger. 304 SS also has higher corrosion resistance and tensile strength. Look at what the major players are using. All the top suppressor companies utilize 304 somewhere in their product lines. Not one uses 303, even in an unwelded design.


p.s. You can hit me up over on ST as 'Wicked' once you get set up.

 

[TGagnon]

Re: Research I have done for my first form 1 can.

I'll most likely avoid doing the welding then to save myself the frustration as I don't want my first can to be a pain. I have also seen that a lot of 17-4 and 316 is listed on sites. If I was interested in using a better material and willing to order it, I could save the 303 for a rimfire project, what would you recommend?
For cutting I will be using HSS cutting instruments 90% of the time as I prefer to go a little slower machining. I know tooling has a lot to do with what you can use but don't yet understand how so figured I would mention it.

 

[Wicked Weapons]

Re: Research I have done for my first form 1 can.

I cut and turn everything with carbide tooling. Sorry, can't assist much with HSS advice. But, start by turning 304/316 SS light and fast and it will not go well I assure you.

316Ss is an improvement over 304, but it's lots harder to get in tubing. Tons of seamless tubing in 304/304L available readily. 316 not so much. Commercial builders order in quantity so they buy sizes/materials you and I can't easily get.

17-4PH once hardened is great for brakes/mounts and blast baffles. It's very easy to heat treat yourself if you have access to an oven that hits 900F. Good luck finding 17-4 in seamless tubing though.

As you've noticed, most cans are built from a combination of metals. It makes sense. Some may only be obtained in one form or another. I once turned an outer tube from solid bar stock as that's the only way I could obtain the material required in the diameter needed. There is also a cost savings, some materials are quite expensive and no better in a specific application than something less costly.

You likely never get this puppy hot enough to require a nickel based steel (Inconel). For a first time Form 1 go-round on a bolt gun:

Outer Tube - 304/304L seamless tubing
End Caps - 316/316L
Baffles - 316/316L
Blast Baffle - 316/316L or 17-4PH
Spacer Tubes - 304/304L seamless tubing

It's free advice, so it's worth only what you paid for it. Keep digging and you'll find it's much harder than you'd think to design/build a decent performing, cost effective F1 can that isn't overbuilt.

 

[TGagnon]

Re: Research I have done for my first form 1 can.

This is going to be bolt guns only at target events. I want to compete in all the F-class events in my area knowing that I won't qualify for wins due to the can. If I can show some people in my area the benefits maybe I can turn a few to the dark side and get another division going that allows cans. Either way it will be fun to try and compete with a can.

On the material selection I might go with a better steel. My friend works on the navy base in the machine shop and they throw out material left and right. I'll ask him to keep an eye out for any applicable materials I could use. Would consider not using inconel but will wait till I can get some more opinions from ST before changing my mind on that. I know it will be easier to move forward with the project if I am not having to track down something harder to get like that.
This project is also waiting on me to get home in march and then send out my papers. I am in Afghanistan and don't trust the postal system here with anything smaller than a flat rate shipping box.

And a huge thank you for that list on materials and uses. Saves me mucho time. Also could I use the 303 I have on a large sized rimfire can without any ill effects? It was going to be steep anyway and a 1.5 inch tube that I could take down to clean. I wanted the extra size on the rimfire can as I shoot 22lr thousands of rounds at a time.

 

[maccrazy2]

Re: Research I have done for my first form 1 can.

14 inches out of ss. That sucker is going to be heavy.
Why bother with the brake design if you dont plan on removing it?
I am currently working on 3 myself. .243, .308 and 50cal. I just ordered some titanium yesterday for the 308 can. The rest will be stainless. I would strongly recomend carbide bits and you have to get after it when cutting. If you let the cutter dwell it will be toast.

 

[TGagnon]

Re: Research I have done for my first form 1 can.

The guns it will be on are already in the 15-24 pound range and there are multiple guns that will be set up to accept this can. Actually most likely it will be the same gun different barrels. I get on it when making initial cuts but when I do finish cuts I cut in smaller amounts ranging from 005 to just skimming the surface.

 

[TGagnon]

Re: Research I have done for my first form 1 can.

Thought I would give an update on this. It appears as though the place I bought my 303 stainless might have sent me 316 all around instead but I will have to wait till I get home to verify for sure. If they did then sweet deal if not then I will end up making a rimfire can for my bolt guns with the 303.