And its still loud. All titanium, 9.5 inches long, 1.5 inch internal diameter. 6 60 degree cones with .65 inch spacing. 2inch blast chamber that the brake sits in. The bore is .390 for optimal clearance if i want to run it on my 9mm. I shot my 556 (mk18) and and 308 (scar) through it i get huge fire balls and not much noise suppression

Anyone?

First off, is it loud with subsonic 9mm?

No, 9mm is fine through it and does well. But with my 5.56 10.5 barrel it might as well not be on there. Itd be like me just taking the muzzle brake off. Shooting at night you get big fire balls. Im thinking maybe adding a rubber wipe at the end or even doing a threaded insert on the endcap thatll make the exit hole smaller. Thoughts?

Do you have another silencer to compare it to?

ETA: Have you shot suppressed rifles before? If you were you expecting it to be Hollywood quiet, they are not.

Rubber wipes are great for low pressure rounds, but even then you get only a few rounds before the rubber blows out. I would get about 8 rounds of nice, quiet performance, then it would quickly degrade with subsonic 9mm and high quality rubber wipe material. This really has it's purpose, but it is limited.

Rifle rounds through rubber is probably a non-start, especially with such a short barrel. You just have too much pressure and fire to keep a wipe from coming apart. In fact, I'd estimate that you could actually have a catastrophic failure if the wipe blows apart, then obstructs the endcap.

Also, it's tough to run a can bored out for 9mm and get performance with a rifle round (particularly supersonic, and out of a short barrel).

I would say your best bet is to use a different endcap for the smaller bullet, but it will take discipline to not put a 9mm through the smaller hole.

Ya two of my buddies have them, ones a specwar and the others an osprey. I know what to expect

Yup ill have to be careful but thats what ill do. Threaded insert to close that endcap hole a bit. Do you have any idea on optimal clearance for those two calibers?

Are your baffles simple cones or do they have turbulence inducing features (sometimes called clipped baffles) to work the gas off the boreline?

0.390 would be a tight bore for 9mm but in-line with most .30 cal suppressors.  Rimfire .22 cans usually bore out at 0.280 for a 6" long tube, so for your length and centerfire 556 cans would be 0.300" and up.  Many .30 cal cans at 0.405" handle 9mm and still sound good on 556 with good baffles.

If your baffles are already clipped you could try reducing spacing near the end cap and get 1-3 more baffles in a tube that long.

Clipping disrupts the laminar plug of high pressure gas that drafts the bullet through the baffle stack. Tight perfectly symmetrical cones are louder than looser bored cones with flow disrupting features.

Short barrels are always louder and harder on cans, especially titanium. Try it on a 16".  If it sounds good on a 16" more baffles and thermal mass will help a little with shorter barrels.

ETA also if your spacers aren't thin titanium you could be losing a lot of internal volume.

Titanium can make huge fireballs come from suppressors. Just what you can expect.

As for sound, quite odd a design this large isn't performing. Even if the cones aren't clipped, you should have better performance.

A question on your build
6 (baffles) * .65 (spacing) + 1 (Blast cone length) + 2 (BC) + 1.5 (end caps) = 8.4in
Where's the rest of you length gone?

My 6.3" build has 8 baffles, lives on a 10" bbl and sounds great.

Personally, I'd have shrunk the spacing and tried to get at least 9 baffles in there.

10.5in barrel in556 will never be quiet

I could try clipping them, just hit them with a ball endmill. The spacing issue might be it. I didnt think of that. They are all the same spacing.

Back endcap is threaded in and is solid. Front endcap is also threaded in and is solid though im thinking about putting a circular radius in it. Also all titanium with one stainless blast baffle.

If you use a single clip with a ball end mill they seem to work best with the clips lined up.  Square end mills also work, but most centerfire rifle baffles seem to use the ball end mill.  I'd be surprised if clipping the baffles and adding 1-3 more doesn't get you very close to a commercial suppressor.

Check out the Form 1 board, they have some good info on how to clip the baffles for better sound.

So i checked it out and one called a double hybrid  clip they say works the best. Should i progressivley get tighter spacing towrad the exit to make room for 1 or 2 more baffles?

Actually mine is not too bad and its a form 1 can. All titanium with 60 degree cones and double clipped.

If you look at some of the cutaway pics of current commercial cans they are packed full of baffles.

MAX,

Be careful with modifying your can. You can still clip your baffles and I would highly recommend the double hybrid clip, it's very easy to do with just hand tools. Legally speaking you cannot 'change/replace' silencer components on a form 1 can after it is completed. Since you have test fired it, it is complete as of that time. You can remove material but not add any, so adding additional baffles is a legal no-no. Try clipping your cones, your suppression should improve. Any changes beyond that, ie 'recoring' the can need to be done by an 02/07 FFL (SOT). They are the only ones that can replace and/or add components to the internals. A can that size should be more than hearing safe, I have a 6.2" form 1 5.56mm can that I shoot on 11.5" SBR and it's comfortable to shoot.

So i clipped my baffle with a .25 ball endmill on both sides 170 thou deep except for the endcap and blast baffle. I also took a .440 ball endmill and gave the front end cap a circular radius (making it baffleish) 350 deep and now this thing is pretty quiet. I think i bored everything to consentric and there wasnt enough disruption

@Torxsteer or anybody else for that matter.

Can you quote the specific statute or regulation with this specific info?

What material can be removed? You'd have to be careful clipping or you could increase the bore size, and now you've made a new firearm.

Glad the clipping improved the sound performance.  For what it's worth, 'clipping' by definition doesn't change the 'caliber' of a suppressor.  If you are opening up the bore in total circumference, that's beyond clipping.

As far as what constitutes a caliber change, as long as one baffle in a commercial can is left to print, the caliber of the can hasn't changed. A normal FFL may repair a silencer if it doesn't involve making silencer parts or other NFA activities.  So for far end baffle strikes it wasn't unheard of in the old days of all welded items for a gunsmith to open up the front cap bore, ream the offending baffle or two, and if necessary weld-filled and rebored the front cap.  None of which made a new suppressor part, or modified the caliber of the suppressor as a unit.

Declaring the 'Caliber' of a suppressor is a regulatory requirement that is beyond stupid. An all wipe suppressor doesn't even have a measurable caliber other than the mount entrance hole and the exit hole, and those have no measurable bearing on what caliber rounds can pass through it.  The Aurora really should be 458 caliber since that's the smallest bore on the 1/2-28 end.  Or maybe it's really a 13.5mm.  If I shoot 9mm through my Harvester 30, have I changed its caliber?

If the engraving on the silencer matches what's written in box 4c, than caliber has not been changed.
My opinion is that the word "diameter" refers to the main body tube size and not the cut bore diameter. A baffle struck bore-line can be reamed w/o need of involving ATF/NFA.

@ImFarmerTed

I'm just paraphrasing what I've seen over the years in regards to NFA ownership. I have read the ATF's NFA handbook a few times but that certainly does not make me an expert on the subject nor do I pretend to be. I've seen a lot of folks swap end caps and/or have spares with different caliber openings or mounting threads. To the best of my knowledge that is a big no-no as each of those would be considered separate silencer parts as they are intended to be used in the construction of a silencer. I'd rather be safe than sorry as I don't feel like becoming a test case for the BATFE.

Just some minor points on the 3 posts above. A ffl 07/02 can make new silencer parts or add cones spacers etc to any properly registered silencer.
A form 1 maker cannot do any of this.

I agree the word diameter means the tube od. I'm not sure about the changing caliber. The only requirement is the can must safely past the bullet of the registered caliber without damaging the internals. So you have a 556 can and you send it to a ffl 07/02  and ask him to bore it out to .375, yes he can since it will still pass the 556.  Another one you have a 30 cal can and want the same ffl 07/02 to replace all the coned and bore to .300. He should not do this since it will not pass the registered 30 cal.

Repairing or recoring a can by a ffl 07/02 does not involve any paper filings or notifications to the atf. You can simply ship the can to the licensed ffl 07/02 and ask him repair or replace or modify what you want done and they send it back. I do this weekly and only require a copy of the approved form 1 for my logbook.

Having multile endcaps for a form 1 can Is definitely a federal  crime unless the endcaps are engraved and registered.

So is there a legal difference between end caps for a commercial vs form 1 can?

Yes, but not necessarily so

An endcap is usually considered a silencer part. Meaning it would need to be made or transferred as such. If a Mfr can prove, to the ATF/NFA, that it serves an alternate purpose, it can be deemed as not a silencer part. Some Mfr's have done this by assigning double duty to their endcaps, for use with brake shields (SilencerCo MAAD Brake Shield). I'm not aware of any Form 1 builder that has attempted or succeeded to get the same status for their personally made parts.

This all stems from the definition of a Silencer:
The term “Firearm Silencer” or “Firearm Muffler” means any device for silencing, muffling, or diminishing the report of a portable firearm, including any combination of parts, designed or redesigned, and intended for the use in assembling or fabricating a firearm silencer or firearm muffler, any part intended only for use in such assembly or fabrication.

Manufacturers are allowed to apply for BATFE variances to certain rules and regulations in the design and build process. For example, a suppressor company can petition the BATFE for a variance for a design that pushes the legal limits that define silencers – extra parts, modularity, etc. Makers, on the other hand, must follow all BATFE rules and regulations as written.

Taken from TheFirearmBlogs post on building a form 1 supressor.