458 Socom - Lets Talk!

Yes, it can be legal to make a silencer. For everything Form-1, from silencer designs that are easily made, to filing forms with the BATF, to 3D modeling. Remember, you must have an approved BATF Form-1 to make a silencer. All NFA laws apply.

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Mattman2010
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458 Socom - Lets Talk!

Post by Mattman2010 » Sat Aug 17, 2019 8:57 pm

Recently bought a 10.5" .458 Socom barrel. Looking into the idea of building a form 1 can for it. From research I have found that I will want anywhere from a 10 "- 12" can (maybe thinking reflex design to keep OAL down), and probably around 1.75" diameter. What I have not figured out is what kind of baffles (cone, K, M, ?). How many? (some people say having fewer baffles and bigger chambers is better), what material (I liked the 17-4 SS that I build my 300 blackout can with) and weather I should just do a welded can, or a tube with a baffle stack. If you have any info, ideas, or advice I would greatly appreciate it!

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Grandpamagnum
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Re: 458 Socom - Lets Talk!

Post by Grandpamagnum » Sun Aug 18, 2019 6:06 pm

You need to G2 the Bowers Suppressors for 458 Socom.
They are recommended by Teppo Jutsu and by Tromix.....the earliest and probably the two best 458 builders around.

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fishman
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Re: 458 Socom - Lets Talk!

Post by fishman » Tue Aug 20, 2019 9:32 am

I have a reflex 450 bushmaster can with K baffles and I like it a lot. I've never shot the bowers 458, obsidian45, or hybrid46, so I don't know how they compare on 450BM.
300 blackout form 1: http://www.silencertalk.com/forum/viewtopic.php?f=10&t=137293

5.56 form 1:
http://www.silencertalk.com/forum/viewtopic.php?f=10&t=141800&p=955647#p955647

Mattman2010
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Re: 458 Socom - Lets Talk!

Post by Mattman2010 » Tue Aug 20, 2019 9:34 pm

Ive been looking at the Bowers. Seems like they use 5 K baffles.

Fishman is that a commercial can that you have or is that a can you built? If built do you have a thread on it somewhere?

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Re: 458 Socom - Lets Talk!

Post by #40Fan » Wed Aug 21, 2019 12:16 am

In his signature.

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fishman
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Re: 458 Socom - Lets Talk!

Post by fishman » Wed Aug 21, 2019 10:08 pm

300 blackout form 1: http://www.silencertalk.com/forum/viewtopic.php?f=10&t=137293

5.56 form 1:
http://www.silencertalk.com/forum/viewtopic.php?f=10&t=141800&p=955647#p955647

Mattman2010
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Re: 458 Socom - Lets Talk!

Post by Mattman2010 » Fri Aug 23, 2019 11:16 pm

Did a quick drawing of my idea of the silencer. Planning on using 1.75 OD x 0.65 Wall 316 SS tubing. 17-4 SS for mount, endcap and baffles. Not sure how to go about locating the blast baffle where it needs to be, or if everything on my K baffles is how they should be. Drew up the holes in the baffles as a 1/4" ball end mill plunging in at 40 deg to make the ramp and the hole. Is there a ratio of bore size to the size of the hole in the baffle cone?

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Re: 458 Socom - Lets Talk!

Post by a_canadian » Sat Aug 24, 2019 3:47 am

Mattman2010 wrote:
Fri Aug 23, 2019 11:16 pm
Planning on using 1.75 OD x 0.65 Wall 316 SS tubing.
Just noting your type, because hey, little errors can become painfully big errors because of typos. If you use stainless tubing with a wall thickness of 0.65" it's going to weigh about 5 pounds. Probably better going with 0.065" wall. But you know that. :D
Mattman2010 wrote:
Fri Aug 23, 2019 11:16 pm
Not sure how to go about locating the blast baffle where it needs to be, or if everything on my K baffles is how they should be.
You're probably going to have to go with a thin-walled tube behind the first K all the way back to the rear plug. Something like 0.035" wall aluminum tubing maybe, or stainless if you prefer. But to keep it lighter you could weld a flat stainless washer to the bit just ahead of the threads, with a bunch of 1/4" holes or whatever fits bored in that to allow gas flow rearwards, and carve a skirt on the blast K baffle such that it meets this washer. Either that or use a cup, like a freeze expansion plug, to weld to the threaded thing with its flange going forward to meet the first K.
Mattman2010 wrote:
Fri Aug 23, 2019 11:16 pm
Drew up the holes in the baffles as a 1/4" ball end mill plunging in at 40 deg to make the ramp and the hole. Is there a ratio of bore size to the size of the hole in the baffle cone?
Generally one uses a ball end mill to match the caliber plus a little, close to the baffle bore size. 1/4" would seem inadequate for this intended projectile.

Mattman2010
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Re: 458 Socom - Lets Talk!

Post by Mattman2010 » Sat Aug 24, 2019 10:02 am

a_canadian wrote:
Sat Aug 24, 2019 3:47 am
Just noting your type, because hey, little errors can become painfully big errors because of typos. If you use stainless tubing with a wall thickness of 0.65" it's going to weigh about 5 pounds. Probably better going with 0.065" wall. But you know that. :D
You knew what I meant :D

I had not thought about a cup with holes in it. I believe that is the route I am going to take. Also changed the ball end mill cut to a 1/2" instead of 1/4".

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Mattman2010
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Re: 458 Socom - Lets Talk!

Post by Mattman2010 » Sun Aug 25, 2019 3:02 pm

So I checked the weight of what this can will be. Not impressed... 40oz. Max psi on 458 socom is around 38,000 psi. How does that translate to a 10.5" barrel? Can I get away with using 1.75x0.065 6061 tubing instead? Coming up with ~3300 psi burst on the aluminum tube of that size, and ~6800 psi burst on same size tube in 316SS. Right now the 316 tube would be around 17.5 oz, changing that to 6061 would be 5.9 oz, with a total weight of 28.4 oz. Right now I have the thinner walls of all the baffles at 0.065", thinking leave the first one that thick and then all remaining baffles down to 0.040" thick. Also need to thin out the reflex mount as it is also 9 oz.

a_canadian
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Re: 458 Socom - Lets Talk!

Post by a_canadian » Sun Aug 25, 2019 6:22 pm

Add to that ECCO's fairly strongly stated sentiment that reflex volumes mean next to nothing in terms of suppression efficiency, and yeah, seems like all that weight is a bit excessive. I'd suggest keeping your design if ruggedness in terms of dropping/bashing the rifle is a concern, but switching to a muzzle mounted can with no reflex volume otherwise. Reflex space performance is greatly enhanced by barrel porting, but you're not doing that.

Sorry, can't address the 6061 question as I've no experience with heavy stuff like this. Thinner baffles after the blast baffle make sense though.

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Re: 458 Socom - Lets Talk!

Post by 3strucking » Sun Aug 25, 2019 9:57 pm

If I were going the reflex route, then I would absolutely port the barrel.

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Re: 458 Socom - Lets Talk!

Post by Mattman2010 » Sun Sep 01, 2019 4:15 pm

I was just wanting to do reflex to save some length. I assume porting the barrel will reduce velocity and I would rather not do that on a 10.5" barrel. I did shoot this thing this weekend. Its breaths fire like crazy and kicks like a mule (Rifle only weighs 6lbs). I did get rid of the reflex part in the design, that cuts out quite a bit of weight, but with the recoil of this thing I am leaning toward a heavier can, but the handguard I have on it now is not the handguard I plan on using so that will end up adding some weight to it as well.

Now on the design I am not sure if I want to keep a bigger blast chamber and stack all the baffles together, or make the blast chamber smaller and add more space between baffles. Or if I just need to add more baffles all together.
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Re: 458 Socom - Lets Talk!

Post by jimb0 » Sat Sep 28, 2019 10:38 am

I am trying to design my own 458 can for a 10.5 inch ar-15. Mine is going to be pinned/welded to the barrel so I won't be going the reflex route. Also doing all I can to make this thing strong enough to last generations so... I started with the highest pressure the blast chamber will probably see. According to this data ( https://ndiastorage.blob.core.usgovclou ... pDater.pdf ) a 10" 5.56 showed pressures around 12000psi at the muzzle (uncorking psi). I need to create a blast chamber that can handle at least that ( 17-4 SS; 1.9"dia; wall thickness 0.129"; UTS 115000psi yields a tube that can handle 15615 psi)

I am not sure how long to make my blast chamber. I assume pressure should be dropping significantly in the subsequent chambers/baffles.

I sourced some 17-4 skirtless cones that are 1.642"dia so my calculations for a tube that is 1.75" OD and uses these cones seems a little too thin (at least for the blast chamber)

Am I on the right track or am I just designing a chunk of over-heavy stainless steel? I don't know...let me know your thoughts and if you have any data/calculations for blast chamber volume.

3strucking
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Re: 458 Socom - Lets Talk!

Post by 3strucking » Sat Sep 28, 2019 11:41 am

If I were going to use that tube I would turn down the length after the blast chamber to something along .030".

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Re: 458 Socom - Lets Talk!

Post by jimb0 » Sun Sep 29, 2019 9:18 am

3strucking wrote:
Sat Sep 28, 2019 11:41 am
If I were going to use that tube I would turn down the length after the blast chamber to something along .030".
Agreed...When I see what a .129" thick wall looks like I keep thinking I have over-engineered this tube.

If that 10" 5.56 barrel produced 12000psi inside the barrel at the muzzle then what would the pressure be in a blast chamber with that is 1.5"dia (vs the 0.223"dia of the barrel)? It has to be less, but how should I calculate that?

--------Just saw ECCO's post on "Internal Ballistics"----------
Re: Internal ballistics

Post by ECCO Machine » Fri Sep 06, 2019 10:52 am
You don't need a computer program to calculate that. You do have to operate under the assumption of certain chamber pressures, though, whether using a computer or doing the math yourself. Unless you happen to have the equipment for testing that...

Boyle's law is a very simple calculation; for every doubling of volume, pressure drops by half and vice-versa (assuming contant temperature). You just need to know case volume less what space the bullet occupies.

5.7x28 has a case volume of about .05 cubic inches if we take away the neck. A .223 caliber bore, if we approximate for rifling lands, will equal that volume every 1.3". 5.7x28 MAP is 50 KSI. So, the first 1.3" of barrel after the case neck will drop the pressure to 25 KSI. The next 2.6" will halve it again to 12,500 PSI. That's 3.9" of bore, which is probably very close to what you have with a 5" barrel that includes the chamber.

Of course, most commercial ammo is running a bit under MAP, so realistically you're looking at probably 10-12 KSI uncorking pressure.

Now, if you're trying to calculate for the operating of your silencer tube, you have to apply Boyles law again. But that assumes a closed system, which a suppressor certainly isn't. That said, operating under that assumption will give you a solid safety margin. Anyway, if the total volume of your case & bore are ~ .2 cubic inches with an exit pressure of 12 KSI and your blast chamber is, well, let's use a nice, round 1.0 cubic inch figure, you'd have a new total volume of 1.2 cubic inches and a pressure in that chamber of 2,000 PSI (if it were sealed).

https://www.omnicalculator.com/physics/boyles-law

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