This cartridge is amazing...

[Old Bob]

Thelaststraw... "Bolt locks on last round every time and ejects 3 to 4 reliably but hammers off the deflector hard. Curling necks and even side dings sometimes."

A small piece of self-sticking velcro on the deflector will keep your brass from getting too dinged up after ejection. You still might get some case-mouth dents but they wont be as bad.

[Thelaststraw]

I ordered a few weights, H1-3 and I'll try some Velcro too. I think I know where I went wrong. Initially many barrels were coming +1 and +2 and light carbine buffers seemed to be a fix if I remember correctly. I think I had that in mind for some reason instead of looking closer at the system I have.  I checked my magazines too, and they are the scallop Grendel magazines. 'Should' be good there.

I appreciate the help and I'll give it another go this weekend one change at a time and report back. I'm pretty confident y'all help sort this out for me now.

[Dino11]

I think forks put to much emphasis on where their brass is ejecting, if it is ejecting at 3 or 4 oclock it should not be hitting the deflector very hard, if it was hitting it hard you would see 1 or 2 oclock. It really does not matter as long as the rifle functions as it should, fires, ejects, strips and chambers next round and locks back on last round.

I would use the velcro and turn the gas down. Hornady brass seems to be a little on the soft side so it's going to deform a little easier. Case mouth deformation is normal for a gas gun and will resize it self when run through a sizing die unless it is pretty much crushed out of shape.

[grayfox]

I have used the spikes (~4.2 oz?) and a kaw valley red (~4.5?) but right now I have a stock carbine buffer in it. Might go to H/H1... IDK.
I have the duramags and they are working well but I might install that front scoop anyway.
Interesting thread.

[Thelaststraw]

It is very interesting how many different successful setups people are running. I have a carbine buffer currently but I'll have to play with it some more. 

  This platform is new to me. I came from USPSA and tuning my CZ production gun was very straightforward compared to this.

[skyrep]

I am using the JP Enterprise AR-15 Silent Captured Spring Gen 2 H2 in my 20" Monster Gas Gun. Have not had any issues and all my brass collects at my 4 o'clock in nice pile. May have one or two pieces of brass with slight deformed mouths out of 50 rounds. Very happy with it.

[SuaSponte]

It is very interesting how many different successful setups people are running. I have a carbine buffer currently but I'll have to play with it some more. 

  This platform is new to me. I came from USPSA and tuning my CZ production gun was very straightforward compared to this.

Tuning gas is an art and a science. Since you have a Superlative Arms AGB, open it up all the way (which is usually ~45 Clicks before the detent stops clicking, it'll go a couple more though). Then fire one. If you get lock back, you'll either need to up the spring rate or the buffer weight (or both if it's really over-gassed). If you don't get lock back, that is a good sign - just turn it in a couple clicks each time, until you do - then go 1 or two more. I'm a Sprinco guy, and use Odin Works adjustable buffers (with additional Pur-Tungsten weights if needed) - but there are a ton of products out there. I like Sprinco, because you can just up the spring rate, which adds zero mass to the system. I don't shoot without a Can so I have no advice on what, exactly, should be a starting point for un-suppressed, but starting at 45 clicks out with what you have now, is #1 IMO.

[Thelaststraw]

Doesn't opening it up past halfway put it in bleed mode? The way I understood how they work was the lower setting up to 18-19ish is normal to restricted. After that is the bleed modes ,which is why I chose it, for shooting suppressed. I would think that it would not be good to bleed when unsuppressed for reliable operation?

Please don't take this as being argumentative, I'm trying to learn this gas system tuning.

***Nevermind, I understand now I think. By bleeding excess gas instead of restricting, it's cleaner running for the gas block and the BCG... Am I on the right track?

[SuaSponte]

Doesn't opening it up past halfway put it in bleed mode? The way I understood how they work was the lower setting up to 18-19ish is normal to restricted. After that is the bleed modes ,which is why I chose it, for shooting suppressed. I would think that it would not be good to bleed when unsuppressed for reliable operation?

  Please don't take this as being argumentative, I'm trying to learn this gas system tuning.

***Nevermind, I understand now I think. By bleeding excess gas instead of restricting, it's cleaner running for the gas block and the BCG... Am I on the right track?

Restrictive Mode can cause seizure, even on SA blocks - it was designed for bleed off mode. Dead Air actually metered a 5.56 gun at every position (0-45), and found that ~30 clicks out gave the best compromise of both port and muzzle dB reduction.



You understand the concept correctly, but if you are overgassed to start with, you have 3 options: Bleed the gas, which adds zero weight; Up the spring rate; or up the buffer weight (or all 3, depending on how bad it is). Going after the gas is easiest. Higher spring rate and/or more buffer weight increases the rearward and forward impulses.

Other than your possible carrier speed problem, just running Carbine/Carbine will usually "work" - but it's usually more gas/carrier speed (wear) than needed. And here's another thing to consider: When tuning a gas system/spring/buffer; different ammo will require different settings, at different temperatures OR just use your weakest ammo at low temps and call it good for everything else.

[Thelaststraw]

Thank you sir for the explanation. I realized that bleeding made more sense and your explaination supports that. I'm in Louisiana and it gets pretty damn hot and humid and we have temp deltas of 20 to 30 degrees. 80 something in the morning and 100 by lunch, probably not as bad as parts of AZ but the environmentals change dramatically.

Basically what your saying is with carbine/carbine, if I can't tame with the gas block which is optimal, then move to buffer. Shooting softer ammo isn't really an option for my use so I have two options really. Thank you sir for the help, it's appreciated greatly.

[SuaSponte]

Thank you sir for the explanation. I realized that bleeding made more sense and your explaination  supports that. I'm in Louisiana and it gets pretty damn hot and humid and we have temp deltas of 20 to 30 degrees. 80 something in the morning and 100 by lunch, probably not as bad as parts of AZ but the environmentals change dramatically.

  Basically what your saying is with carbine/carbine, if I can't tame with the gas block which is optimal, then move to buffer. Shooting softer ammo isn't really an option for my use so I have two options really. Thank you sir for the help, it's appreciated greatly.

I personally like (based on info from Sprinco Customer Service) to up the spring rate before increasing buffer weight; less mass = softer shooting. But you can do either. With a Can, I need to do all three. My 11.3" 5.56 is a beast - Sprinco Orange, Odin Works Heavy with 3 Tungsten (~6.8oz), and the SA AGB at 30-45 clicks out, depending on ammo (with a Rugged Razor).  The 6 ARC is close, but only needs an H3 (about 1oz less).

[Thelaststraw]

Rather than starting a new thread, I thought I would just add to this since it relates to the same rifle. I got my gas dialed in and my SA gas block is superb for handling both suppressed and unsuppressed fire( which rarely happens,lol)

Currently it's a 20" monster but I have an itch to assemble an upper with a longer barrel to get all I can out of this, with a gas gun at least. I'm leaning toward 24" but 22" isn't out of the question. My goal is 2800fps at approx 1-2000 DA in order to maximize BC. I imagine there are diminishing returns at or above 24 but 'think' it should just about do it. Any input from the more knowledgeable ones?

The other thing is gas system length....would going plus 2 or even 3 be beneficial as far as dwell time since it's pretty much always suppressed? An extra 2 to 4 inches of barrel is quite a lot and I can't fully wrap my head around that specific aspect of dwell time and bolt unlocking optimally or early, etc.

I'm going to a Precision rifle class this fall and these guys mean business, I don't want to fall short when things get out past 1k.

[Thelaststraw]

It's been pretty quiet around here but figured I'd give an update. After talking to the folks at Compass Lake, I have a 24" rifle +2 barrel coming my way in the (somewhat) near future. Should be a soft shooter and I'm sure will more than exceed my expectations.....and my ability for a good while.

[SBRSarge]

TLS,

That should be a great barrel. Be sure to post up some groups when you get it dialed in.

[Thelaststraw]

TLS,

That should be a great barrel. Be sure to post up some groups when you get it dialed in.

   I appreciate the kind words. I want to stress the fact that I'm not displeased with the Monster in any way whatsoever. I just want a heavier profile and a little longer for a better balance when the rifle is on barricades.

   I'm pretty excited though, I already get some serious speed and  consistent groups. I'm not so hot punching paper since I spend most of my time practicing positional stuff. I'll get some pics up of what I have so far, although I'm the weak link.

[SBRSarge]

TLS,

That should be a great barrel. Be sure to post up some groups when you get it dialed in.

   I appreciate the kind words. I want to stress the fact that I'm not displeased with the Monster in any way whatsoever. I just want a heavier profile and a little longer for a better balance when the rifle is on barricades.

   I'm pretty excited though, I already get some serious speed and  consistent groups. I'm not so hot punching paper since I spend most of my time practicing positional stuff. I'll get some pics up of what I have so far, although I'm the weak link.

Better to be the weak link than the missing link!

I have a Monster barrel too, the 12 inch one. So far I only have a few rounds through it but I like it. I might get out to the range this week and try for some good groups with it.

[KenC]

Brief background first...
I'm from the communist territory of NY originally and moved to Louisiana
Discovered I could easily buy firearms
Bought firearms 
Started shooting USPSA about 5 years ago
I let my pistol primer stash get low and hit the rifle primer lottery a few times....

  Present time....ran across a 20" Monster barrel a few weeks back and had a lonely Aero M4E1 Enhanced receiver set laying around so everyone here knows what had to be done. I was interested in the cartridge from launch but wanted to be sure it wasn't another Valkyrie first. I'm fairly certain it's here to stay and it's the real deal. I never shot past 100yds before nevermind zero a scope. I tend to research stuff to death and overanalyze everything...I don't know, it's subconscious, but helps me sometimes. 

   I'll get some pics when I get a chance but it's nothing spectacular currently, still waiting on some backordered items still in a production run. My entry rig to PRS/NRL type events before dropping big coin on a chassis. I did a rough sight in  and tracking test at 50yds and took her to 100yds. Had a rough time with first extraction problems then feeding issues. Big dummy forgot to open my SA adjustable block....at all!      LOL      Still think its not lined up right and have it too far back from muzzle to the shoulder. I'm new to the AR platform but have built a few and nailed it in the past. Short Blackouts with pistol gas, maybe the ports are bigger and less fussy? I'll have to feeler gauge it like I should have.

   Anyways, after a hasty, and I mean hasty 1.5MOA zero at 100 I dialed in for the 600 yd steel. This is what amazed me about the 6ARC....18mph gusty/switching wind 90 degrees to shooting azimuth, 24' elevation, 82 degrees and 70% humidity, only 4.1mil elevation and 0.4mil windage.....not ideal atmospherics for the new guy I imagine, and it was within 1 foot POA-POI with no chrono data and a noob driving! I meant to feed geoballistics 2625 velocity but put 2725 and it hit low for what ever reason. I didn't range the target but I was impressed as you can tell I'm sure.

    So quick question, am I on the right track with the gas block being too far back and undergassed? (Brass ejecting between 3 and 4 with authority just not feeding next round at all or jamming on ramps, regular carbine buffer, 108 ELD Match factory loads.)
****HMMMMM, need to figure out HOW to post pics now...lol****

Hey! Where are you? Louisiana shooter here, also. Drop a PM if you want.

[Bigdaddyjak]

I have built 3 so far with 20” monster barrels. Plain non adjustable gas block, and carbine buffer setup. I have basically 3-4 boxes thru each rifle and the all operate flawless. Maybe had a few fte issues, within the first few shots but after that the all run great . Have u tried to message the feed lips on the magazines at all ??

[Thelaststraw]

I have built 3 so far with 20” monster barrels. Plain non adjustable gas block, and carbine buffer setup. I have basically 3-4 boxes thru each rifle and the all operate flawless. Maybe had a few fte issues, within the first few shots but after that the all run great . Have u tried to message the feed lips on the magazines at all ??

  I got my Monster barrel dialed in after toying with the gas. Around the time the failures got bad was right when I started using my suppressor....when it was 90+ degrees. Turned out my rifle was way overgassed and was having timing issues. Loading with different powders and fully opening my gas block to max bleed got everything running smooth. I use ASC 10 round Grendel magazines and ASC 15 round ARC magazines trouble free.

  I just got a new barrel in about 2 weeks ago and will be giving my 20" Monster to my wife. Nothing wrong with it, just wanted a longer tube.

[BluntForceTrauma]

My MONSTER barrels have the gas port located closer to the gas block shoulder by 0.020 (if memory serves) because I don't anticipate users using these barrels with M16 handguards and their handguard cap.

So, correct positioning with a MONSTER barrel is to butt up your gas block to the gas block shoulder and then the gas ports SHOULD be aligned.