another modular suppressor question

[garredondojr]

I was just reading on another forum that as long as you do it correctly you "can" lawfully build a modular suppressor?

For example I'm wanting to build a 9mm can like some of the commercial cans that allow a K configuration (short) here's what they mentioned of safe ways to keep it legal. i'd like some input from you guys on your thoughts or if you know if this is legit or not.

say the F1 was submitted as 8" long as long as the suppressor is 8" or short in the full length configuration your good.
2nd there must be no spare parts when in the full length configuration. (ok makes sense)
now this is where I get confused. as long as the extension and baffle stack on the modular part is unable to be used as a separate suppressor your good. (um ok but how does the tube extension and baffles not constitute "spare parts"?)

They mention making the tube extension with a male thread will help keep the atf happy as it isn't readily changeable into a 2nd suppressor without spare parts to do such with.

if this is truly ok to do i'm sold! i'd love to do a 1.375"x5" with a 3" extension to make a 1.375"x8" I'd even be willing to weld the baffle stack together and plug weld it to the extension tube for that extra safety margin.

any advice?

[T-Rex]

I believe a modular may have been posted before. I don't see why it couldn't be legal.

Look up the definition of "spare". Not saying this is always reliable, but it's the only reference you have.
A spare tire isn't needed for normal operation and is only implemented as a replacement to a regular part becoming damaged.
This doesn't really fit the removable portion (which, personally, I wouldn't call an extension).

Making mating sections not easily adaptable to readily restore it into a separate suppressor would be smart. Not sure if 100% necessity, but smart.

[garredondojr]

Just thought of something that I feel would make this entirely safe to do.

If I used a tube with a thicker wall thickness on the modular section (good idea on not calling it an extension)

not only would this be needed to have sufficient material to thread it but the baffle stack for the modular section would have a smaller OD therefore the baffles within that stack would not be spares as they would not fit in the lower section as they would just bounce around in the tube.

[crazyelece]

There are two landmines to avoid.

1) you are not allowed to make "spare parts" - so make sure that your design would include features such that a baffle from one section couldn't replace a baffle (or spacer) from the other. I'd say different dimensionally or welded stack would be appropriate.

2) that the parts not used in the "k" configuration could not be used to create a silencer in and of themselves - this is the tricky part

On one hand there is no law that says you can't use your silencer without all the parts, but it also says that silencer parts are silencers. So if ATF deems your unused parts as "spare parts" it would end baddly

Personally, as a form1 builder, I design and build my silencers for a single purpose, and therefore have never bothered with the modular design. If it were me, I would build 2 different silencers or buy a commercial modular design if it was available for what I was trying to accomplish.

[fishman]

I would also add that there must be a possible configuration that uses all the parts. the length of this configuration is your OAL on your form 1

[garredondojr]

There are two landmines to avoid.

1) you are not allowed to make "spare parts" - so make sure that your design would include features such that a baffle from one section couldn't replace a baffle (or spacer) from the other. I'd say different dimensionally or welded stack would be appropriate.

This is exactly what I was thinking. I'd make the ID of the module smaller and thus the baffles as well. I would weld the stack for added insurance.

2) that the parts not used in the "k" configuration could not be used to create a silencer in and of themselves - this is the tricky part

My thoughts here were to thread one end of the module with a male thread the same as the endcap then the other end would be threaded for the endcap so no way to make it a silencer on it's own without a 2nd end cap and some way to convert the male ~1.2" thread to a muzzle.

On one hand there is no law that says you can't use your silencer without all the parts, but it also says that silencer parts are silencers. So if ATF deems your unused parts as "spare parts" it would end baddly

Personally, as a form1 builder, I design and build my silencers for a single purpose, and therefore have never bothered with the modular design. If it were me, I would build 2 different silencers or buy a commercial modular design if it was available for what I was trying to accomplish.

I agree with this to an extent. I'm all for doing it the legal way which is what I'm trying to seek answers for. Thats one thing about the gummyment I don't care for. There typically very thorough about rules and regs. but when it comes to the grey they always have the upper hand.

[Hannibalbarca]

Just make it normally, don’t do different Id or anything like that.
No ones going to care, manufactures make it like that, no reason you aren’t able to as well.

[ECCO Machine]

I there must be a possible configuration that uses all the parts. the length of this configuration is your OAL on your form 1

This is the key.

The internals of your can don't become new silencers just because they're removed for cleaning, but extras are a problem.

The precedent for modulars exists, just mimic existing designs.