Tuning 556 gas system

[BurtG]

Does everyone agree with this chart ^

I’m getting brass at 1-2 o clock to get the bolt to lock back

Razor core 77gr
Jp fmos
20” barrel
Tbac 338 ultra can.
Jp gas block

Also. This gun I bought used. Finally tore it down to diagnose spent cases not ejecting and the extractor only has one spring ?

 

[Cascade Hemi]

Is that a JP bolt?

 

[BurtG]

Is that a JP bolt?

Looked it up. Lwrc apparently

 

[Cascade Hemi]

I'd sort out the missing parts first.

As far as tuning the gas system. Close the gas system. Open it until the BCG locks back. Open a little more. Ejection pattern isn't universal.

 

[JohnDeereGuy1996]

View attachment 8465738

Does everyone agree with this chart ^

I’m getting brass at 1-2 o clock to get the bolt to lock back

Razor core 77gr
Jp fmos
20” barrel
Tbac 338 ultra can.
Jp gas block

View attachment 8465742

View attachment 8465743


Also. This gun I bought used. Finally tore it down to diagnose spent cases not ejecting and the extractor only has one spring ?

View attachment 8465740

That’s most likely your extraction issues. I’d replace both with new.

Home

DetailsJust like their buffer springs, the Sprinco AR-15 Extractor Springs are made from high quality Chrome Silicon wire stock that has been heat treated, stress relieved, and cryogenically processed to produce long lasting durability. This 5 coil extractor spring upgrade kit is designed for...

www.primaryarms.com

 

[joe777]

What buffer system parts? I see there's a law folder on it

 

[BurtG]

What buffer system parts? I see there's a law folder on it

Gun ran perfect though multiple 250+ round gas gun matches last year.

 

[mettee]

Mk262 is hotter than Razor core 77? If the razor core is softer that would explain this. Try less buffer weight.

 

[M4orturnate]

Order a sprinco spring kit and o ring and try it. Might as well do gas rings while you're at it for the extra 5$
Edit or throw a different bolt in there to see if it runs first

 

[BurtG]

throw a different bolt in there to see if it runs first

Cleaned and lubed. Adjusted gas so it locks back. Seems to run good now. But brass is at 1-2oclock

Probably going to swap in a low round count jp bolt for a match here on Saturday

 

[M4orturnate]

Cleaned and lubed. Adjusted gas so it locks back. Seems to run good now. But brass is at 1-2oclock

Probably going to swap in a low round count jp bolt for a match here on Saturday

Wish I could make it. Hopefully next month

 

[BurtG]

Wish I could make it. Hopefully next month

I might be able to get to that 1. Probably not though work is life.

 

[joe777]

Side note how do you like the 338 can on a 20" 5.56? Gotta imagine it's nice

 

[drglock]

Run the same gas block on my Noveske with 18” Douglas barrel, TBAC .30 Ultra 9 shooting 77 Razorcore. Ejects in the same 1-2 clock as you. Don’t remember my setting on the block but I’m in the full bleed off mode.

 

[BurtG]

Side note how do you like the 338 can on a 20" 5.56? Gotta imagine it's nice

Works well.

 

[hlee]

Did you replace the missing extractor spring? I wouldn’t do too much ejection pattern diagnosis until everything else was sussed out.

 

[BurtG]

Did you replace the missing extractor spring? I wouldn’t do too much ejection pattern diagnosis until everything else was sussed out.

Supposed to be delivered today.

I swapped jp bolt in last night Il do a function verification later

 

[232593]

Supposed to be delivered today.

I swapped jp bolt in last night Il do a function verification later

Did it work?

 

[The Knuckle]

It’s possible that there’s not enough dwell time, meaning the case is still expanded inside your chamber while it’s trying to extract, requiring more gas to blow the bolt back.
A heavier buffer would be easiest but an enhanced 3 port lmt bolt bleeds off some of the gas causing a delay in extraction.

 

[softcock]

What buffer system parts? I see there's a law folder on it

That's all I do is just start out closed and open till it last Round mag. holds Bolt and give one more Clik of open.

I got a few of the Superlative Adj.GB's .
to the Law Folder .. I did experience a little Gas hinky BS on the last build I did this year. I almost had to open the friggin GB totally Open to Last Clik to get last Round hold open . On a 16" Mid.length 5.56 gas set-up . I actually had to remove significant amount of buffer weight to keep it 100% reliable.
But .. I just chalked it all up to having added the Law Folder unit to the entire equation that FuckedUp my state of normalcy .
.

 

[BurtG]

Did it work?

Yes but needed more lube also

 

[232593]

View attachment 8465738

Does everyone agree with this chart ^

I’m getting brass at 1-2 o clock to get the bolt to lock back

Razor core 77gr
Jp fmos
20” barrel
Tbac 338 ultra can.
Jp gas block

View attachment 8465742

View attachment 8465743


Also. This gun I bought used. Finally tore it down to diagnose spent cases not ejecting and the extractor only has one spring ?

View attachment 8465740

What kind of mount do you have that ZCO in?

 

[BurtG]

What kind of mount do you have that ZCO in?

Zco.



Tier1 is another one that looks great

 

[Huskydriver]

If your extractor and ejector are not working that will certainly effect your ejection pattern.

The chart is a guide but not law. When I build my own I go for what locks the bolt back with my can, then usually give it 3,5 more clicks to cover unsuppressed and reliability... My ejection is usually never 3 perfectly when I do this but it's usually the least amount of recoil while still bring reliable suppressed vs non

 

[ktm131rob]

Is that the spent case in the chamber or an unfired? If it’s unfired I have had that symptom and it has been an over gassed issue.

 

[232593]

@BurtG are the TBAC cans able to be disassembled by the user for cleaning?

 

[BurtG]

@BurtG are the TBAC cans able to be disassembled by the user for cleaning?

No.

Throw that thang in the ultrasonic.

Or just run it

 

[232593]

Works well.

Damn, do you even need earpro with that setup?

 

[BurtG]

Damn, do you even need earpro with that setup?

Everyone comments how quiet it is.

But all supersonic ammo causes hearing damage. And I’ve killed a lot of mine already