3 lug adaptor, barrel shoulder questions

[nimdabew]

I am contemplating putting a 7.5" barrel on an AR-15 in 9mm but the handguard I want to use is an SLR 6.7" rail. That 6.7" is top rail length and the shoulder for a 7.5" barrel is apx 6.5" from the reciever to the shoulder.

When I get a suppressor with the 3 lug attachment and mount, I am worried that the rail I want will have the back end of the suppressor touch the front of the rail because of the .2" overlap from the shoulder and the front of the mount.

Those of you with a 3-lug suppressor and mount: how much extra space is there from the shoulder to the back of your suppressor is there, and how much of the mount is exposed? In other words, how much length is there from the back of your suppressor and the shoulder of your barrel when the suppressor is mounted on your firearm?

[wct097]

Looking at mine, when I'm pressing the suppressor on to engage/release the mount from the 3-lug, the very back of the can/mount is pretty much even with the back of the 3-lug mount and the face of the barrel shoulder. I took some close-ups, but it's still somewhat hard to see since my mount is slightly recessed under the handguard.

Looking down into the handguard from the front:
https://wct097.com/wt/guns/sbr/9mm/m4c/3l-1.jpg

Looking in through the rail, notice how the barrel flares out to have a shoulder then the color of the metal changes and you see the 3-lug on the end:
https://wct097.com/wt/guns/sbr/9mm/m4c/3l-2.jpg

Looking into the can's mounting adapter:
https://wct097.com/wt/guns/sbr/9mm/m4c/3l-4.jpg

Can installed (Gemtech Multimount):
https://wct097.com/wt/guns/sbr/9mm/m4c/3l-3.jpg

Can being pressed backwards to install/remove:
https://wct097.com/wt/guns/sbr/9mm/m4c/3l-5.jpg

Note, slight angle because i'm pressing and holding the phone at the same time, so I suspect the can/mount doesn't go beyond the end of the 3-lug over the barrel shoulder, but it's right there. There certainly isn't 0.2" of gap between the barrel shoulder and the end of the can/mount. I think you're going to be out of luck if you use the same 3-lug mount that I have and have a rail too small to fit over the overlap with the can. Mine is a HK 3-lug that I bought from Gemtech on a Kaw Valley 4.5" with 1/2-36 threads. I've seen some 3-lug mounts that have a longer shoulder that might work for your setup, if your barrel is threaded 5/8-24 or 13.5-1LH. Griffen Armament sells those and states that they've got a cylinder extension machined onto them. http://www.griffinarmament.com/Revolution-3-Lug-Adapters-p/93l.htm

http://image.prntscr.com/image/38985d2f0aef41a49566cb9bf862bf55.png

On a side note, if you want a 7.5" 9mm barrel threaded in 1/2-28, PM me. I have my old one that I'd be willing to sell:
https://wct097.com/wt/guns/sbr/9mm/barrel.jpg

[nimdabew]

That's exactly what I wanted to see. If I had checked here before buying an 8" barrel, I would have purchased your 7.5". Thanks for the pics and everything else!

[wct097]

That's exactly what I wanted to see. If I had checked here before buying an 8" barrel, I would have purchased your 7.5". Thanks for the pics and everything else!

Happy to help!