Lower has arrived; I NEED DESIGN HELP, PLEASE !

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.

Moderators: mpallett, bakerjw

Post Reply
PyroGuy
Member
Posts: 31
Joined: Tue Feb 21, 2012 9:07 pm

Lower has arrived; I NEED DESIGN HELP, PLEASE !

Post by PyroGuy » Thu Mar 07, 2013 1:49 pm

Arrived yesterday; a GWACS Armory Polymer AR Lower (279.00 Fully Populated ! ) that I have designated to be an integral suppressed 9MM using Sten Mags.
If this were a straight can, I would have a plan, but since it will be integral,I have no idea how to proceed. I have available to me:
CNC Turning
CNC MIlling
Manual Turning / Milling
Anodizing/Black Phosphate Coating (HonHart Black)
I want it to look nice, and be perfect; prefer MonoCore baffle design, as I can't have an SBR in michigan, and the shroud has to be 16"
A dedicated upper is 2K, I would like to do this for half that, which seems reasonable.
I will post pics of the build.
I apologize for NOT doing that with my last build.
I would like this by the end of December, so the form 1 better go out soon.
Thanks in advance for your help.

crazyelece
Senior Silent Operator
Posts: 125
Joined: Fri Jun 06, 2008 10:08 pm

Re: Lower has arrived; I NEED DESIGN HELP, PLEASE !

Post by crazyelece » Thu Mar 07, 2013 1:54 pm

you could design it like a thread on and then drill and pin to perm attach to get the 16+" overall length

PyroGuy
Member
Posts: 31
Joined: Tue Feb 21, 2012 9:07 pm

Re: Lower has arrived; I NEED DESIGN HELP, PLEASE !

Post by PyroGuy » Thu Mar 07, 2013 2:05 pm

I would prefer that the Monocore drop into a shroud. I looked at a 7 1/2 pistol upper, with the idea of permanat mounting to that, but wouldn't it be better to have larger volume at first, like an MP5SD ?

Thanks for your reply. How do I post photos ?

User avatar
L1A1Rocker
Silent But Deadly
Posts: 3578
Joined: Wed Feb 21, 2007 7:40 pm
Location: Texas Hill Country

Re: Lower has arrived; I NEED DESIGN HELP, PLEASE !

Post by L1A1Rocker » Thu Mar 07, 2013 2:35 pm

I'm assuming that you are in a country that does not require "papers" for your build.

I'd try looking through this thread first: viewtopic.php?f=10&t=79895

Lots of good designs there, and some are integrals.

crazyelece
Senior Silent Operator
Posts: 125
Joined: Fri Jun 06, 2008 10:08 pm

Re: Lower has arrived; I NEED DESIGN HELP, PLEASE !

Post by crazyelece » Thu Mar 07, 2013 5:24 pm

L1A1Rocker wrote:I'm assuming that you are in a country that does not require "papers" for your build.

I'd try looking through this thread first: viewtopic.php?f=10&t=79895

Lots of good designs there, and some are integrals.
No He's in MI he'll need papers for the suppressor, but they don't allow SBR.

OP I was thinking of a monocore design in which the barrel side endcap and outer tube are one piece. Make it thread on but perm attach. Then the monocore, including the exit side cap, threads out of the tube. Or vice versa with the monocore being pinned and the outer tube coming off, depending what makes more sense once you start drawing it out and designing it. Hope that makes sense!

pnl2012
Senior Silent Operator
Posts: 118
Joined: Wed May 30, 2012 10:29 pm

Re: Lower has arrived; I NEED DESIGN HELP, PLEASE !

Post by pnl2012 » Thu Mar 07, 2013 7:01 pm

This is not what you are looking for but can give you some ideas and clues (or I hope so): http://grabcad.com/library/300-blackout ... onics-only

DMY
Senior Silent Operator
Posts: 136
Joined: Tue Feb 12, 2013 10:27 pm

Re: Lower has arrived; I NEED DESIGN HELP, PLEASE !

Post by DMY » Thu Mar 07, 2013 9:06 pm

Wow, so with a 7-1/2" barrel, that leaves you about 9" of suppressor. That's a really good starting point.

Have you considered going with a shorter barrel? Not 100% sure about this (I am sure there are countless details and variables) but I'm not sure that a 9mm benefits from a longer barrel. You might be able to go with a shorter barrel and even more suppressor volume without losing anything.

Also, do you have a target as far as width is concerned?

PyroGuy
Member
Posts: 31
Joined: Tue Feb 21, 2012 9:07 pm

Re: Lower has arrived; I NEED DESIGN HELP, PLEASE !

Post by PyroGuy » Mon Mar 11, 2013 4:14 pm

Regarding width, I'm going with my wife's suggestion that wider is better. :)
Given 16" OAL, is there some formula for barrel length ? I shot my friend's DeLisle, and the volume in that can really seems to make a difference, so I want to barrel to be the "Proper" length, but nobody seems to know what that is
If a straight blowback will work, then that's the way I will go; I was always under the impression a gas tube was preferred. The way the state requires this thing be build is a little archaic, but I should be able to make it work.
SO;
A 7" Bbl that shoulders into the proximate end of the monocore, a blast chamber of X length, then the baffle sections, then an I.D. threaded end cap with spanner holes.
Any value in venting the barrel ?
I'm assuming the whole monocore would have compression O-Rings for centering, probably in 3 places with 9" OAL
Make sense ?
Thanks

DMY
Senior Silent Operator
Posts: 136
Joined: Tue Feb 12, 2013 10:27 pm

Re: Lower has arrived; I NEED DESIGN HELP, PLEASE !

Post by DMY » Mon Mar 11, 2013 10:03 pm

PyroGuy wrote: Given 16" OAL, is there some formula for barrel length ?
I wish there was an easy formula, but there is not. There are so many design variables and there is (relatively) so little shared knowledge that it's tough to set out a formula. Testing is difficult due to NFA restrictions and of course the cost to build and test one design after another. Further, a lot of people with the knowledge and experience to answer these questions are reluctant to volunteer the information for one reason or another. Your best bet is to post up a design, get a few "that won't work because..." suggestions, and modify it from there.

It seems like most form 1 builds wind up emulating what mainstream manufacturers are doing. With that being said, GemTech has made versions of their 9mm AR TALON upper with barrels that are about 5" and 7" in length.
PyroGuy wrote: If a straight blowback will work, then that's the way I will go; I was always under the impression a gas tube was preferred.
I think most 9mm AR setups do not have a gas tube.
PyroGuy wrote: I'm assuming the whole monocore would have compression O-Rings for centering, probably in 3 places with 9" OAL
Thanks
You lost me with the 3 O-rings - doesn't sound like something you see in a lot of 9mm designs. Usually the tube end(s) are threaded and that's it. Some use O-rings on the ends.

SinjinSmith
New Member
Posts: 4
Joined: Mon Jan 21, 2013 12:21 pm

Re: Lower has arrived; I NEED DESIGN HELP, PLEASE !

Post by SinjinSmith » Wed Mar 13, 2013 3:34 pm

PyroGuy wrote:... as I can't have an SBR in michigan, and the shroud has to be 16" ...
Have you considered designating the lower as a pistol? My personal preference is for longer barrels (14.5+ because torch-eroded baffles makes baby jesus cry), but if you'd like shorter, you can go shorter and still stay away from an SBR stamp.

Edit: NVM. I see now it's a polymer lower with integrated stock...

chevcamo
Silent Operator
Posts: 60
Joined: Tue Sep 08, 2009 4:39 pm
Location: Hammond, LA
Contact:

Re: Lower has arrived; I NEED DESIGN HELP, PLEASE !

Post by chevcamo » Wed Mar 27, 2013 2:16 am

I'd do something like this.
viewtopic.php?f=10&t=77234

You get a full length barrel while still being integral. And since you have the CNCs the hard part should be drawing it up.

The first part of designing something like this thought is making the decision on barrel length, after that it's fairly simple. I'm stuck on an integral MKIII .22 because I can't make up my mind how long I want the barrel to be, but I know I don't want the length to be any longer than 6" from the front of the receiver.

Post Reply