30 cal build idea

[Meb959]

Hey guys I plan on building a 30 cal can on a form one in the near future! I haven’t submitted a form one yet just trying to get a plan together before submitting. I want to do a 30 cal can for use on a CZ scorpion sbr, ar15 14.5”, and a .308 probably 16” or 18”. I’m not trying to be super quiet with it I just want to be hearing safe is all and no plan to shoot subs through it. I want to build a 6” can with a 1.5” od with a ti grade 9 tube and spacers with ss 17-4 60* cones with a 1.5” blast chamber while using a Q cherry Bomb style muzzle brake but longer for my 14.5 to pin and weld and a ss 17–4 threaded cap for the brake and a ti end cap. Does this sound like it might work or do I need to go a little bit longer?

[John A.]

I have an 8 inch 9mm that sounds OK on the scorpion.

The 11 inch sounds a lot better though.

308 would not be hearing safe with either of them. And I'm positive that it certainly wouldn't be with a 6 inch can either.

Oh, and not to be condescending, you can't shoot 9mm through 308 unless it's overbored to almost .400 rather than .350'ish that I would normally do for a blackout or 308.

That may have been what you meant, but I learned long ago not to take anything for granted by assuming and just wanted to mention it.

[Meb959]

That was the plan to over bore so I can use for 9 mm. I really like the Deadair Sandman k so that’s why I want to go shorter instead of longer. I want to go as short as possible to be hearing safe with a 308. I am open to maybe a 2” od

[T-Rex]

If you're going through all the trouble, why settle for less?
Going from a 1.5 OD to a 2" will increase initial weight by 35%, not counting the 90% more your end caps will be. You could use an 8" length of 1.5 tube and have a much better design, and be < the weight of the larger one. A longer, narrower tube, with more baffles, will outperform a shorter and fatter one.

For those new to form 1 silencer making, there's no need in waiting to formulate a design. File for a 12" silencer, to get yourself in the queue. You have the ability to change the approved length and caliber, prior to making. It's as simple as a signed letter, emailed, faxed, or mailed to the ATF. There's no need to wait for a reply, albeit wise. However, they usually don't take more than 10 days to send a confirmation letter. I know recent times have shown speedy approval turnovers, but, take it from someone who's waited over 18 months for an approval, you want it in and back ASAP.

[Meb959]

Good points T-Rex maybe I will go to an 8” length and 1.5 od, but I am in no hurry to submit a form one due to the happy wife happy life philosophy right now but if I bug her enough she will cave! When I submit I will start with a 8” length and change if needed

[John A.]

That was the plan to over bore so I can use for 9 mm. I really like the Deadair Sandman k so that’s why I want to go shorter instead of longer. I want to go as short as possible to be hearing safe with a 308. I am open to maybe a 2” od

That sounds good on paper.

However, doesn't really correlate with what's feasible in the real world.

Not busting your chops. I would be ecstatic if you could pull it off. But I wouldn't bet on it.

[Meb959]

That sounds good on paper.

However, doesn't really correlate with what's feasible in the real world.

Not busting your chops. I would be ecstatic if you could pull it off. But I wouldn't bet on it.

Yeah it sucks we only get one chance for a build and then stuck with that result, that is why I am doing as much reading on this subject as I can so I can get a good end result! I’m glad I found this forum!

[Hannibalbarca]

If you're going through all the trouble, why settle for less?
Going from a 1.5 OD to a 2" will increase initial weight by 35%, not counting the 90% more your end caps will be. You could use an 8" length of 1.5 tube and have a much better design, and be < the weight of the larger one. A longer, narrower tube, with more baffles, will outperform a shorter and fatter one.

For those new to form 1 silencer making, there's no need in waiting to formulate a design. File for a 12" silencer, to get yourself in the queue. You have the ability to change the approved length and caliber, prior to making. It's as simple as a signed letter, emailed, faxed, or mailed to the ATF. There's no need to wait for a reply, albeit wise. However, they usually don't take more than 10 days to send a confirmation letter. I know recent times have shown speedy approval turnovers, but, take it from someone who's waited over 18 months for an approval, you want it in and back ASAP.

Closer to 48 percent or almost twice the volume, 8.6 vs 16.3 cubic inches

[T-Rex]

It's not just about the bore dia, either. A 9mm suppressor has a different set of requirements than one for 308. Smaller caliber bullets typically work best in larger cans that are designed for a like platform. Like a 9mm through a 45 or a 5.56 through a 7.62. Yes, the bore is much larger than the projectile, but the volume is almost always larger and compensates for any loss w/ bore efficiency. The bottom line is, you'll be much happier with purpose built designs. If I were in your shoes, I'd start with one for 9mm, which can handle the 308 and, later, build one for 5.56/7.62 double duty. This would alter your initial expectations and plans, but offer you a bit of reprieve, for a while.

The wife needs to understand that suppressors are a must have item

Closer to 48 percent or almost twice the volume, 8.6 vs 16.3 cubic inches

I was speaking solely about the weight. While a 1.5"OD x 6" tube (.058 wall Ti) will weigh ~4oz. A 2"OD x 6" will be ~5.5oz. Yes, the volumes will be close to 8.3 & 15.3 cuin, respectively, once the mount is deducted. However, I very rarely credit much to pure volume. Plenty of designs have shown how baffle management can impact performance greater than volume alone. Baffle count, coupled with design, along with: spacing, bore dia, and clipping style are my top priorities. From the existing examples of years passed, we can easily extrapolate a good starting point. Experimenting and tuning is what gets you the gold.

[John A.]

It's not just about the bore dia, either. A 9mm suppressor has a different set of requirements than one for 308.

Your opening sentence is a thread winner.

OP, when you're dealing with supersonic rifle rounds and subsonic pistol calibers, what works in one is not likely to work as well in the other. And the same holds true for the other way around. If it did, there would be no need to have more than one kind of baffle.

The first can that I built way back in the early 2000's, was done in 9mm, but built strong enough to handle 308, 7.62x39, 6.8spc, 243, etc. I thought, I could build a single universal can to use on everything I owned, which I did and it worked "ok", but I quickly learned why all the manufacturers weren't doing the same thing. It didn't work near as well as I thought it should in rifle calibers.

While it works really good in 9mm (totally ignoring the 11 inch length), rifle rounds are still loud as crap through it if you're going to compare it to dedicated rifle cans in that caliber. Not only is the bore of a 9mm huge when shooting 223 through it, the baffles are not as effective for supersonic rifle rounds either. While it does work and muffle the sound of a rifle shot, it's still obnoxious without muffs and that's just being bluntly honest.

So, I'm seriously not wanting to shoot down your concept, but I've already been down that road and know what's at the end of it and why I wanted to share almost 20 years of doing this.

In the end, I ended up building multiple cans for different calibers and different guns anyway. I have 2 (soon to be 3) detachable cans that I can move around and for those times when I really am serious, I have 3 integral suppressors if you're going for the epitome of quiet, go for broke and do dedicated integrals and design and build something that you know is going to work well.

If you're just wanting something to take the edge off, yeah, that will work, but if you want something that's going to work well, you need to design the can around what and how you're shooting.

[Meb959]

Thanks guys for all the great info! Now I think I will work on doing a 9mm can that will be similar to a omega 9k because I shoot more 9mm than rifle rounds, and I don’t have a 308 yet so maybe I’ll do a 300blk instead because I know that will work with a 9mm can. And women will never understand the need for all of the guns and gun related stuff that is so important!

[fishman]

I was speaking solely about the weight. While a 1.5"OD x 6" tube (.058 wall Ti) will weigh ~4oz. A 2"OD x 6" will be ~5.5oz.

Yes, but the baffles and caps will be significantly heavier. It will be closer to 77% heavier overall.

Scaling up 2 dimensions:
(2" * 2") / (1.5" * 1.5") = 1.77 ~= 77% heavier

Instead of making it 77% heavier width-wise, make it 77% Longer and it will perform much better. The only downside is that the overall length of the gun is longer, and the weight is balanced slightly more forward.

[T-Rex]

Yes, but the baffles and caps will be significantly heavier. It will be closer to 77% heavier overall.

My words were misinterpreted, by Hannibal, and so I clarified them.
You must have missed my first post where I said the other parts would also weigh more, including:

not counting the 90% more your end caps will be

Scaling up 2 dimensions:
(2" * 2") / (1.5" * 1.5") = 1.77 ~= 77% heavier

This works great for squares, but not sure how it would apply to two cylinders of differing dimensions with varying amounts of internal material. I do agree, as I've always said, you're better off with a longer, narrower design. In terms of both weight and performance.

Instead of making it 77% heavier width-wise, make it 77% Longer and it will perform much better.

Are you suggesting he make the suppressor 10-5/8"?

[ECCO Machine]

Closer to 48 percent or almost twice the volume, 8.6 vs 16.3 cubic inches

Math isn't your strong suit, is it?

Before accounting for end caps & internals:

2.0 OD x 6" long .062" wall has 16.6 CI internal volume

1.5" OD x8" long .062 wall has 11.9 CI internal volume

As well, there is such a thing as too much internal volume, especially for low pressure, low powder capacity rounds. I've had to get very creative with recores on some .22 rimfire and 9mm cans that had too much volume for a conventional baffle arrangement to work properly. When there's insufficient gas pressure & volume for the features of a baffle to do what they're designed to do, you get lots of laminar flow, ergo more noise.

Of course, T-Rex was talking about tube & cap weight, not internal volume anyway.

It's not just about the bore dia, either. A 9mm suppressor has a different set of requirements than one for 308.

This is the most important consideration in your proposal, OP. "Do all" cans tend to perform worse than more dedicated models in most if not all categories. High pressure supersonic rounds need a completely different baffle profile & spacing than small pistol cartridges. And opening up your bore to pass 9mm bullets is going to hurt .308 performance even if the can size, baffle profile a& baffle spacing are optimized for .30 supersonic rifle. I have a 1.8x10" model for .375 caliber magnum rifle that works fantastic on the .338 & .375 magnums for which it was designed, but actually performs worse than my 1.5x9" Furtivus on smaller rounds like 6.5 CM and .308 Win.

[fishman]

This works great for squares, but not sure how it would apply to two cylinders of differing dimensions with varying amounts of internal material. I do agree, as I've always said, you're better off with a longer, narrower design. In terms of both weight and performance.

it should work for scaling up two dimensions of any 3D shape. Of course, a 2" silencer is not exactly a scaled up 1.5" silencer, but 77% should be a close approximation.

Are you suggesting he make the suppressor 10-5/8"?

I was merely pointing out that a long skinny can of the same weight will perform better.

I do have an 11" 30 cal silencer though.

[ECCO Machine]

This works great for squares, but not sure how it would apply to two cylinders of differing dimensions with varying amounts of internal material. I do agree, as I've always said, you're better off with a longer, narrower design. In terms of both weight and performance.

it should work for scaling up two dimensions of any 3D shape. Of course, a 2" silencer is not exactly a scaled up 1.5" silencer, but 77% should be a close approximation.

It's actually not too far off with 1.5" vs. 2" (74% greater weight), but that's dumb luck. When you step up from 2" to 4", the math no longer works even for back of the napkin estimations; (4*4)/(2*2)=4, but the actual weight increase with, say, .062" wall for both, is 103%, not 300%. Going from .75" to 1", you'd also get 1.7777e, but 1.0" .062" wall is just 36% heavier than 3/4"

For tube, you have to use πr2*length for OD then subtract πr2*length for ID and multiply by the volumetric weight of the material in whatever unit your volume calculation is. Or you could just plug it in here:

https://www.industrialmetalsupply.com/Weight-Calculator

[fishman]

It wasnt dumb luck, its a mathematical approximation.

When you step up from 2" to 4", the math no longer works even for back of the napkin estimations; (4*4)/(2*2)=4, but the actual weight increase with, say, .062" wall for both, is 103%, not 300%

Like i said, "of course a 2" silencer is not exactly a scaled up 1.5" silencer, but 77% should be a close approximation."

I understand that pi is involved, but it cancels out when you scale something up proportionally.

Of course 2" to 4" doesn't work, because the proportions of a 4" can are way different than a 2" can.

If you take any 3d shape and scale it up by double the length, width, and height, it will weigh exactly 8 times as much. It doesn't matter if its a cube, sphere, cylinder, silencer baffle, or a dodecahedron. (2*2*2)/(1*1*1) = 8

The math works with only 2 of the three dimensions as well. But only if you're proportionally scaling up the shape.