lightweight, Suppressed SBR questions

[A5scott]

So, I have a 308 (dpms style) lower that I have engraved, and will fill out ATF forms to SBR it. The same goes for an LWRC 556 lower.

I understand that permanently attached (pinned/welded) suppressors aren't the best idea as far as cleaning and versatility. I currently have 2X 308 cans as well as a 556 can. Weight and length are the biggest driving forces of my new SBR builds, and I will buy new cans for the 308 and 556. I travel to other friendly states, so that is the motivation for permanent attached suppressors. I also know about the ATF form to travel with SBR's.

I was looking at the Griffin Armament Spartan 3 for 556. it's 12.5 ounces, with flats to pin and weld, or simply torque. Fairly inexpensive as well. Griffin claims their can needs no cleaning.

for the 308, I was looking at the Sig SRD 762. 15 ounces, direct thread with flats to pin/weld/silver solder.

I understand legal advice questions should be answered by the ATF or attorneys etc., but:

is silver soldering a legal way to permanently attach a muzzle device to satisfy the 16.1" barrel length requirement? or pin and weld only?

I may get a 10.5" LWRC A5 upper unless there are some other really good suggestions for a 10.5" 556, running suppressed all the time.

looking for options to build a 12.5" 308 dpms style upper.

I'm considering Aero upper/keymod handguard, and a ranier 12.5" ultramatch bbl, but the bbl is 30 ounces. I would like to find a lighter option.

I like piston guns, but am completely open to and own DI guns as well.

thanks so much for any responses!
all the best
scott

[ginzomatic]

is silver soldering a legal way to permanently attach a muzzle device to satisfy the 16.1" barrel length requirement? or pin and weld only?



This is from the NFA handbook:

"The ATF procedure for measuring barrel length is to measure from the closed bolt (or breech-face) to
the furthermost end of the barrel or permanently attached muzzle device. Permanent methods of
attachment include full-fusion gas or electric steel-seam welding, high-temperature (1100°F) silver
soldering, or blind pinning with the pin head welded over. Barrels are measured by inserting a dowel rod
into the barrel until the rod stops against the bolt or breech-face. The rod is then marked at the
furthermost end of the barrel or permanently attached muzzle device, withdrawn from the barrel, and
measured."

So yes, you should be good. There is a lot of speculation however on how much of the base should be welded (quarter, half, full). Whenever I run into things like this I just call them and ask.

[ginzomatic]

I may get a 10.5" LWRC A5 upper unless there are some other really good suggestions for a 10.5" 556, running suppressed all the time.




Almost forgot, check this thread out:

https://www.m4carbine.net/showthread.php?33743-Best-Suppressed-SBR-Ever

[Rayrevolver]

Nothing against LWRC, but isn't the A5 really heavy at 4.8 lbs?

I have not weighed my lightweight 11.5 suppressed only upper, but a 16" BCM ELW KMR13 weighed 2.75 lbs. Figure the BCG+CH is 0.85 lbs, and you are at 3.6 lbs and a 10.5/11.5 could weigh less depending on barrel profile. Adding the Spartan to this 16" upper makes it 4.4 lbs and its still lighter than a bare A5 upper.

Lots of good info in the thread above. Also lots of threads about using a LW or BCM ELW profiles on suppressed only uppers on M4C.

Another option instead of a small ported barrel is to choke the flow at the gas block. You can get port inserts to tune your gun to the suppressor and not have any additional moving parts associated with an adjustable gas block.

Getting a suppressor only gassed DI upper with a BCM KMR (or other light rail) makes for a very light rifle. I almost went with the Spartan but decided to go the cheap route with a Gemtech Trek (17oz). Even with the Trek out front on a lightweight 11.5 barrel (17oz) I have a really nice carbine to shoot.

I just bought another LMT E-carrier to try with my setup.

EDIT: Clarified statement about Grants SBR thread. I meant to say we have discussed using LW profile barrels for suppressed only shooting recently, but not in Grants thread.

[jstalford]

AFAIK, you don't need to fill out a form to transport suppressors across state lines. Only SBRs.

[A5scott]

AFAIK, you don't need to fill out a form to transport suppressors across state lines. Only SBRs.

yes, I believe this to be true, which is why I'm looking to permanently attach the suppressors.

thanks for the replies! I'm checking that posted thread now

scott

[A5scott]

and yes, the LWRC A5 is on the heavier side. I did handle a full A5 SBR and it felt pretty good, compared to some other SBR's that felt sort of like bricks.

I have a couple LWRC IC's and they run well, and if I was going to get something out of the box GTG, that would be my first thought, though you're right, it does defeat the weight POU. But I was thinking that The A5 would run, without having to swap out parts. And then I thought I would post up here to get other ideas.

Scott