Suppressors KAC fixed gas block rifles fire both sup/unsup. How can I build my AR10 to?

[Praetorian_6]

Fellas,

I have a nice Aero Precision M5E1 with a 16" barrel & mid-length gas. I ordered a KAC MAMS and will have QDC suppressors (CQB & PRS) from knights.

All I've read indicates that adjustable gas blocks are not reliable (leakage, carbon lock, failure). So, if I can avoid using one while being able to operate with and without a can, I'd like to. So, how do I get that done?

If your position is that it can't be done, then at least please recommend the most reliable AGB in your opinion.

Thanks!

 

[hlee]

Build a 300 blackout with an 8.5” barrel and pistol length gas. No adjustable gas block required to run supers or subs, suppressed or not.

Adjustable gas blocks get an unfairly bad reputation. Those that say they are unreliable are probably the same ones that say that 45 it God’s caliber, that reloads will get you killed in a gun fight, and that an aftermarket trigger is a go to jail free card in a self defense scenario...

Most reliable adjustable gas block? SLR rifleworks sentry series gas block...

 

[Zak Smith]

IMHO, the Seekins low profile adjustable is the most reliable adjustable gas block, though adjustment is not quick. I have used the SLR and don't anymore.

 

[blbennett1288]

You could try gas port tuning. This is what I am trying on my LMT MWS

Black River Tactical Store - Shop BRT

Shop BRT Black River Tactical Store Covert Comp OPTIMUM EZTUNE Gas Tube MicroTUNE Gas Block CustomTUNE Gas Port MicroPin Gas Block Mk12 Gas Tube BRT EXT BRT EXC BRT PDW Pistol Carbine Mid Midlength Rifle Upper Receiver Group Bolt Carrier Group Barrels Muzzle Devices Adjustable Gas Drive AR15 LMT

blackrivertactical.com

 

[Praetorian_6]

hlee, I've got an SR30 on order to take care of the 300 BLK. It's a 9.5, but something tells me it'll work just fine sup/unsup. Otherwise, I hear you guys on the AGB. I'll do it if I have to.

@blbennet1288, thanks for showing me that. I've never heard of them. It looks like it's just a matter of picking the correct tube, and then it vents off gasses at the gas block. I'll look into it more. Have you had any success with them?

Anyone got any ideas on how to make a 16" mid-length .308 AR10 work both sup & unsup with a fixed gas block?

 

[Zak Smith]

Besides the BRT gas tubes blbennett1288 mentioned, you can also look at the JP VMOS and SCS to change the reciprocating mass.

I have no qualms using the Seekins Adj gas block, it is solid and gives you more configurability.

 

[blbennett1288]

@Praetorian_6 I have not had a chance to test it out yet. My LMT MWS is excessively over-gassed suppressed. I found the BRT Gas Tube suggestion in the LMT MWS thread here. There are a few in that thread who have used them and had good results.

 

[Jackalope]

There’s also adjustable bolt carriers. The Bootleg is adjustable with a flat head through the ejection port. Super easy and no carbon locking.

 

[Praetorian_6]

I like those ideas. Replacing the BCG & buffer masses seems like a good, albeit expensive solution. The adjustable BCG seems cool too, but bootleg's site is only showing an AR15 version.

That's probably all she wrote, right guys? Either change the mass of the system, or adjust the gas pressure in some meaningful way.

Seems to me that if knights has tuned their systems to work both sup & unsup, then the adjustability is only needed once. What's the likelihood I can get away with finding the right fixed weight buffer & BCG? I weighed Knights' BCG right at 20oz. My Aero Precision BCG is 18.4. I do not know what size gas block or tubes they use. I believe they continue to use full rifle length gas systems. So, there are quite a few variables to figure out, if I try to reverse engineer it for myself.

 

[Zak Smith]

IMO, the most bang for buck is adjusting the gas, even if you just do it once and then leave it (and do subsequent tuning via mass).

 

[Praetorian_6]

Gotcha Zak. I agree. I'm just worried about reliability down the line if/when the gas block starts leaking. Is that an unreasonable concern?

 

[Zak Smith]

Examining the design and history of parts to make sure you aren't compromising the reliability of a rifle is a good idea. I don't use the SLR gas blocks anymore. I won't use a single-set screw adjustable gas block either. I have no problem using the Seekins adj. gas block, it has a double set screw design, and if you're still nervous put some high temp loctite on one of the screws, it'll never move.

 

[Praetorian_6]

Sounds like the way...

 

[db2000]

IMHO, the Seekins low profile adjustable is the most reliable adjustable gas block, though adjustment is not quick. I have used the SLR and don't anymore.

I agree with Seekins from personal experience. Cans, no cans and full auto both ways in 5.56. I don’t adjust anything and have never had any problems with several thousand rounds. I did initially have to make adjustments in FA with subsonic .300 blk but now it runs cans on/off without adjusting. That gun has considerably less rounds than my 5.56’s

 

[Ape_Factory]

2A Armament also makes an AR10 adjustable BCG btw...as does Rubber City Armory. I like the 2A's design a bit better as there's no need to remove the BCG to tune the gas. I like RCA's BCG due to their coatings and option for the POF roller cam pin. They're amazing.

Take a look at Superlative Arms. Their adjustable gas block has the ability to restrict AND to bleed off at the gas block. This can be beneficial with normal suppressor (not flow through) designs which exhibit more back pressure. Due to the design of the block, it won't freeze up either. With that said, I have a normal, restrictive gas block on my 308 AR and after around 2500 rounds, it turns just fine (POF Dictator gas block). It does, however, leak a bit but the rifle functions as it should. I pulled it apart to clean it a few days ago for the first time just for shits and giggles and see if that's what was causing the leakage issue. I went with a flow through suppressor to have as few tuning issues as possible and to be able to run with and without, no adjustment needed.

 

[Praetorian_6]

Thanks for the feedback. Apparently KAC will be coming out with the flow through suppressors next year. But mine are the current gen ones.

I went ahead and ordered the Seekins AGB recommended above. We'll see if the rifle functions reliably first and then install it if it doesn't. Household 6 fires leftie anyways. So, maybe keeping the gases down is a good idea.

 

[m1ajunkie]

I run a surefire socom mini 762 on my SR25 ECC 100% of the time. My opinion it's over gassed and I actually wish I could tune things. Not a huge deal though as it's still reliable, just primarily an annoyance for me.

I'm running PRI adjustable gas blocks on my LMT MWS 18" .308 barrel and 20" 6.5CM barrel. Prior to going to the adjustable gas block I was getting doubles out of the rifle I assume from excess bolt speed. After the adjustable gas block I was able to tune things down where the doubling went away and brass ejects at 3-5 o clock depending on which barrel.

I'm a fan of adjustable gas blocks but my purpose is tuning for 100% suppressed.