Aero/Sig Shorty 308

[jtallen83]

Wanted a DI gun to replace my Sig P716 jam-o-matic. When I saw CDNN clearing out the 12.5 inch Sig barrels used for the P716 I figured what the hell. The Sig parts are mostly DPMS compatible and CDNN had a bunch of them including the bolt. Gas tube length was the only big difference I had to deal with. Parts list;

Aero M5 blem receiver set and 10 inch rail, Tactical Grey Cerakote

Sig 716 12.5 inch barrel, chrome lined, .073 gas port

D. Wilson Carrier and firing pin with a Sig 716 dual ejector bolt.

Cotton Arms Adjustable Gas Block 

11 inch gas tube custom made by White Oak Armament.

Vltor RE-10/A5SR: A5 Receiver Extension (had to add 50 cents)

PWS MOD2 Carbine Buffer - H3 5.5 oz

Tubbs Flat Wire Spring

LaRue MBT trigger

DPMS upper parts

Aero LPK

Magpul MOE-K2+ Pistol Grip

PSA branded SB3 adjustable pistol brace

This build comes in just over 1 pound less than the P716 at about 8.5 pounds. Much better balance than the 716 and more rail length to work with. The "brace" being adjustable and using a carbine extension tube is the schit! I was thinking the port would be small but no way, I had to crank the gas block way down and it isn't broke in yet. 25 rounds down the pipe and no malfunction except the two fired at the tightest setting of the gas block, ejected but did not lock back. Worked with Lancer and Magpul mags. The bore has to be dead on concentric with the threads, best looking suppressor alignment I have seen to date with the gauge looking dead nuts center. Hope to get the PA 4x16 on it this weekend and see what it will group as well as check out how it reacts to some heat.

Brass ejects about 3-4 o'clock with no suppressor, no swipe, pretty light primer strike;

With the suppressor they land about 1 o"clock and show a little ejector smear;

[98Z5V]

HOT DAMN, BROTHER!!!  It's running WELL!!!  

[Rsquared]

That thing looks SWEET JT. But everybody knows that I'm an SBR fanboy. (yes....I see that it's a "pistol" build).

[jtallen83]

Finding the Lancer mags not so reliable in this rifle pistol. Ran 50 rounds of M80 ball today, Federal and some Austrian stuff. When using the lancer mags the bolt catch engages the carrier and not the bolt, when I cycle it by hand it grabs the bolt. Ran from high to low on the gas settings with no changes till it is choked down and doesn't cycle. With P-mags it grabs the bolt 100% unless the gas is choked way down. On occasion it will drop the Lancer mag out on the last round, I was going to swap the mag catch for an Armalite A model catch but with the bolt catch issue it looks like I will just stick to P-mags. Possibly I have an out of spec Lancer mag.

Accuracy was nothing great but didn't expect much with M-80 ball and using an early PA 4x16 Mil Dot scope that I have never gotten good results from, has a VERY tight eye box, very tight eye relief, and a funky parallax adjustment. Hoping to pick up a more permanent optic on holiday sales coming up.

[willbird]

So what is the story on the Sig barrels ?? What does one need to to to use one in AR 308 ?? Kind of looking at the Aero upper/lower myself.

"Only fits Sig Sauer 716 rifles. Will not work with any SR25 or AR10 platform."

 

[98Z5V]

Custom gas tube.  That's about it. 

[willbird]

Forgot to say nice build :-).

But back to the Sig bbl, does it require the sig bolt to match ?? The custom gas is not a super big deal I suppose.

Bill

 

[jtallen83]

On 12/21/2018 at 7:22 AM, willbird said:

Forgot to say nice build :-).

But back to the Sig bbl, does it require the sig bolt to match ?? The custom gas is not a super big deal I suppose.

Bill

 

I am running the Sig bolt in it but it headspaces and runs on a D Wilson 308 bolt as well. Gas block hangs over the step by a bit to line up the ports so if it were one of those blocks that has an opening in the clamping surface it may not seat well. An SLR gas block jig was a big help getting the dimples in the correct place. Just bought a second barrel when they had them for $49.99, DPMS style bolt headspaces on it as well. Don't forget to grab a 716 bolt catch as well, works in everything I have tried it in.

Edit: Just had a Sig 716 bolt catch not fit in an Aero receiver I just got, odds are just a little thinning and it would have worked though.

Edited October 4, 2019 by jtallen83

[willbird]

Nice info :-). What did the gas tube end up costing for a custom ??

Bill

[jtallen83]

1 hour ago, willbird said:

What did the gas tube end up costing for a custom ??

Right around $40, obviously custom with the polish and the very well done bends and ends. Mine was 11 inches but I highly recommend you measure with your gas block in place to be sure.

[willbird]

Yes it is a good exercise to measure. I want to draw the whole assembly up on cad as a cross section to show the actual interface with the BCG.

[308kiwi]

NICE

You forgot to tell us what suppressor you are running..........

[jtallen83]

24 minutes ago, 308kiwi said:

NICE

You forgot to tell us what suppressor you are running..........

I have a couple AAC SDN-6's.

[98Z5V]

7 hours ago, jtallen83 said:

I have a couple AAC SDN-6's.

One is a reman, though...       I still can't believe how they wrote that up, and completely took care of you. That's just badass. 

[jtallen83]

29 minutes ago, 98Z5V said:

One is a reman, though... 

Good as new! 

[98Z5V]

They are badass, brother.  Completely. 

[RedRiverII]

Late to the party,  but damn that's a beauty.  

[Albroswift]

On 9/5/2018 at 6:11 PM, jtallen83 said:

Wanted a DI gun to replace my Sig P716 jam-o-matic. When I saw CDNN clearing out the 12.5 inch Sig barrels used for the P716 I figured what the hell. The Sig parts are mostly DPMS compatible and CDNN had a bunch of them including the bolt. Gas tube length was the only big difference I had to deal with. Parts list;

Aero M5 blem receiver set and 10 inch rail, Tactical Grey Cerakote

Sig 716 12.5 inch barrel, chrome lined, .073 gas port

D. Wilson Carrier and firing pin with a Sig 716 dual ejector bolt.

Cotton Arms Adjustable Gas Block 

11 inch gas tube custom made by White Oak Armament.

Vltor RE-10/A5SR: A5 Receiver Extension (had to add 50 cents)

PWS MOD2 Carbine Buffer - H3 5.5 oz

Tubbs Flat Wire Spring

LaRue MBT trigger

DPMS upper parts

Aero LPK

Magpul MOE-K2+ Pistol Grip

PSA branded SB3 adjustable pistol brace

This build comes in just over 1 pound less than the P716 at about 8.5 pounds. Much better balance than the 716 and more rail length to work with. The "brace" being adjustable and using a carbine extension tube is the schit! I was thinking the port would be small but no way, I had to crank the gas block way down and it isn't broke in yet. 25 rounds down the pipe and no malfunction except the two fired at the tightest setting of the gas block, ejected but did not lock back. Worked with Lancer and Magpul mags. The bore has to be dead on concentric with the threads, best looking suppressor alignment I have seen to date with the gauge looking dead nuts center. Hope to get the PA 4x16 on it this weekend and see what it will group as well as check out how it reacts to some heat.

Brass ejects about 3-4 o'clock with no suppressor, no swipe, pretty light primer strike;

With the suppressor they land about 1 o"clock and show a little ejector smear;

One question,  Tubbs flat wire spring 

Did you use a 7-5/8" tube with the brace?

Put mine together last night with the 7" tube that came with the brace and spring, completely compressed, would not allow BCG to catch on the bolt catch. Good 1/2" clearance without Tubbs spring, actually need 50 cents or so to clear the ears. 

[jtallen83]

Just now, Albroswift said:

One question,  Tubbs flat wire spring 

Did you use a 7-5/8" tube with the brace?

Put mine together last night with the 7" tube that came with the brace and spring, completely compressed, would not allow BCG to catch on the bolt catch. Good 1/2" clearance without Tubbs spring, actually need 50 cents or so to clear the ears. 

Yes, Vltor RE-10 is the same length as the Armalite AR-10 extension. I put the 50 cents in to get the bolt a little closer to the catch when all the way back, didn't want it slamming the catch to hard. I'm thinking I put a Tubbs spring in my Matrix build but I may be thinking of something else, did a bunch of buffer and spring combo changes when I got my suppressors. From the Tubbs video you should not be having that issue though, very curious to see what the deal is.

[Albroswift]

7" tube,  5.8 oz 2-1/2" buffer.

Put a 7-5/8" tube on it and a 3-1/4" buffer and a 1/8" hdpe spacer (didn't have 50 cents left) things look good. That Tubbs is a raskel to install that's for sure.  

[98Z5V]

1 hour ago, Albroswift said:

7" tube,  5.8 oz 2-1/2" buffer.

Put a 7-5/8" tube on it and a 3-1/4" buffer and a 1/8" hdpe spacer (didn't have 50 cents left) things look good. That Tubbs is a raskel to install that's for sure.  

Sounds like a Rock River LAR-8 buffer.

[Albroswift]

 I know I'm going to get a cussing here but I just turned a longer bumper out of HDPE for the 5.8 oz 2-1/2" KVP buffer. 

[98Z5V]

15 hours ago, Albroswift said:

 I know I'm going to get a cussing here but I just turned a longer bumper out of HDPE for the 5.8 oz 2-1/2" KVP buffer. 

Hell no, man - That's pretty smart. Put up some pics of that weirdo sometime.   

[Albroswift]

nothing fancy

 

 

 

Hey, the paper clip is working beautifully,  multiple uploads at once 

 

[98Z5V]

3 hours ago, Albroswift said:

Hey, the paper clip is working beautifully,  multiple uploads at once

That part has been cracked now - fixed.  Any other issues, let it be known in this section:

https://forum.308ar.com/forum/60-site-news-and-support/