Buffer Spring question for the AR Gurus

[Lungbuster13]

Ok, I’m not a brain child when it comes to the AR’s. I have a few and don’t get overly crazy with filling them up or customizing them. I’ve always been more enamored with bolt guns. That being said, I have a brand new Ruger SFAR with a 20” bbl in .308 that will not cycle subsonic brass with my suppressor on. It has an adjustable 3 position gas block and I have tried it in all three settings unsuccessfully. I was recommended by some buddies to look at upgrading the buffer spring first before I got too in depth. Problem is that I have no idea what spring I need. Any info or a link would be greatly appreciated.

[Lungbuster13]

Anyone?

[Bowtech38]

Be an easy thing to try.

[JuDGe]

Does it cycle supersonic ammo suppressed and unsuppressed?

What is the weight of buffer?

[Lungbuster13]

Does it cycle supersonic ammo suppressed and unsuppressed?

What is the weight of buffer?

I haven’t tried subs through it without the can on. I have no idea on the weight of the buffer. I could look online at factory specs I’m sure. I’m just kind of a greenie on the ar stuff.

[KoonceCrushed]

The buffer and or spring itself can effect the cycling if your gas pressures are to low to blow back the bolt.

[Lungbuster13]

The buffer and or spring itself can effect the cycling if your gas pressures are to low to blow back the bolt.

Yah, I guess that is what my question is…like I’ve tried adjusting the gas block to all three positions and still haven’t been able to throw subsonic brass with my suppressor on. It won’t open the bolt and eject. So I’m curious to know which buffer weight and spring to try replacing the factory stuff with to see potential better cycling.

[Clay C]

If you go light enough to cycle the subs, chances are you are going to have malfunctions with supers.

[JuDGe]

Check this out: https://youtu.be/OMXd8nzE5LQ

[JuDGe]

I haven’t tried subs through it without…

Not subs, how does it cycle SUPERsonic ammo?

[muzzlebrake]

If you go light enough to cycle the subs, chances are you are going to have malfunctions with supers.

Sure will. I use 3 different lowers, each one set up differently. Also use adjustable gas tubes on my uppers. .233, 6.8SPC and 300 AAC
Each one tuned so it ejects at the correct angle and don't dent the brass. I also use David Tubb flat springs to reduce harmonics and noise.
I sometimes use a brass catcher since I'm too lazy to bend down and pick up my spent shells.

[Lungbuster13]

Not subs, how does it cycle SUPERsonic ammo?

I don’t know. I haven’t tried running any SuperSonic ammo through it. I want it to run subs through my suppressor and is strictly gonna be for that.

[imyomama]

gonna try to keep it short ... 20" sfar has long gas system.. and port hole is designed for high pressure of supers ... so unless you plan on making this a sub only gun , it's just not going to happen. you can make the port hole bigger , but then no more supers for you..

if you want to shoot sub 308 caliber , 300blk is a much better choice ..

i have one I built with a noveske 300blk barrel and side charge upper ... i'd trade you. i have too many 300blk ..

[LWD]

This is a video on the SFAR. Skip to the 14:18 mark for information about running different buffers in this gun. [ame="https://www.youtube.com/watch?v=FcXM5SXjVFg"]https://www.youtube.com/watch?v=FcXM5SXjVFg[/ame]

[Chase4556]

I’ve never heard of anyone running subsonic 308 in an AR platform. So I’m no help on tuning it. However, I will say I really like my JP Enterprise captured buffer spring for my subsonic AR shootin. Takes a lot of action noise out, and you can tune them and might get it to cycle the 308.

To play devils advocate and because I’m curious, why not just get a 300blk for the subsonic application?