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Old December 10, 2017, 00:29   #1
grumpy1
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Teach me about adjustable gas blocks

Ok, Iím in the process of building an AR15 in 6.5 Grendel. From what Iíve dug up on the internet, is that the Grendel needs to be tuned to run smooth. The only adjustable gas block I have is on my FAL.

So my question to those who have an adjustable gas block, which one do you have? And also how easy is it to adjust?

For some background, the rifle is being built for a dual purpose rifle, a hunting rifle for my daughter and a 1000+ yard rifle. Thereís a place locally that does a milk jug challenge that starts at 1000 yards and goes out from there. The barrel is a 20 inch 5R barrel, LAR OPS4 side charge upper, LAR Lower. Looking at a Timney trigger and not sure about lower parts kit. Iíve got a Leupold VX3 4.5-14 x50 LR scope to put on it.

Thanks for your help
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Old December 10, 2017, 04:43   #2
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For your application would suggest the Superlative Arms gas block. Has 30 easy to change detent settings and bleeds excess gas out of block keeping bolt carrier group cleaner. If we're building a suppressor gun might suggest different but for your application the Superlative should give you all you need at a fair price.
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Old December 10, 2017, 09:33   #3
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I have tried assorted adjustable gas blocks, and by far my favorite are from SLR: https://www.righttobear.com/SLR-Rifleworks-s/1875.htm

The adjustments are easy and intuitive. Seven positions on most gas blocks, which is more than enough for dialing in your gun. Not only are you adjusting your rifle for suppressed/not suppressed (if you decide to do so later down the line), but you are also tailoring the rifle to the specific round (some of our LEO rounds are significantly hotter than some training ammo).

These gas blocks run clean, are easy to disassemble and clean if necessary (have yet to do so with any of mine). They are very low profile, and come in multiple diameters and mounting configurations.

SLR also has excellent customer service.
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Old December 13, 2017, 06:50   #4
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Two kitchen table AR pistol uppers wandered in yesterday built to circumvent a second stamp as a real SBR. Both were having multiple issues with reliable function and taken to a guy running a gun shop out of his home. His answer was open the gas ports on both. (Daniel Defense uses an 0.083 oversize gas port so all those expensive rifles are over gassed so customers running cheap ammo don't send in as warranty issue)

Now both are having multiple over gas issues and trying to explain to owners why they need an $150ish gas block if want to run both suppressed and unsuppressed without carrying tool and remembering how many turns of a grub screw are required when snap can on or off. Both want a magic solution to gun running smoothly can on or off without making any changes. Or spending more money. Showed both the MicroMOA Govnah and the Noveske switch block and Superlative Arms as inexpensive option. The MicroMOA and Noveske builds change setting without tool but neither want to remove muzzle device, gas block, install proper block that costs what it takes to push, flip or twist and run.

Showed them several blocks where would have to l carry a Allen wrench and remember how many turns to set gas going either direction and they don't like the cheap option either. Both are breaking extractors and bolts along with having bolt over top round failure to feeds now when were short stroking before last smith opened them up. Asked if tried swapping buffers before opening ports to more blank stares. Either this new guy working on AR's must not understand implications of properly gassing and choosing buffer on a rifle that goes from suppressed to unsuppressed or like s to sell replacement parts.

Both owners said wives are a bit peeved that after buying all the parts including Geissele trigger on one, Timney on other, suppressors, wrestling with, confused, took to smith and are now having to replace broken parts. Guys have spent and spent, taken to a "gun smith" spent more and now being told that they need to spend more on a proprietary gas block and possibly a buffer swap are both overwhelmed because internet said just screw the Legos together, snap can on, snap can off, pull trigger. Imagine being over $1,500 into an unreliable AR.

Why I pin my cans and do rifle builds. Not stuck with pistol gas system and buffer trying to make an SBR. So much easier with carbine or mid length gas and rifle buffer assembly. Never broken a part even with can on and running binary mag dumps till gun was smoking. Even showed them videos of how just how hard an AR can be run and function without breaking parts. Won't be surprised to buy one or both "pistols" on the cheap as they try to recoup a few dollars to put into a factory built gun rather than try one last option.
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Old December 13, 2017, 07:20   #5
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Quote:
Originally Posted by lockjaw View Post
I have tried assorted adjustable gas blocks, and by far my favorite are from SLR: https://www.righttobear.com/SLR-Rifleworks-s/1875.htm

The adjustments are easy and intuitive. Seven positions on most gas blocks, which is more than enough for dialing in your gun. Not only are you adjusting your rifle for suppressed/not suppressed (if you decide to do so later down the line), but you are also tailoring the rifle to the specific round (some of our LEO rounds are significantly hotter than some training ammo).

These gas blocks run clean, are easy to disassemble and clean if necessary (have yet to do so with any of mine). They are very low profile, and come in multiple diameters and mounting configurations.

SLR also has excellent customer service.
There are more adjustable blocks available now than ever.

I had an SLR on an AR10T match rifle assemblage several years ago and it was fantastic.

They make quality products and I would buy one again, if needed.
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Old December 14, 2017, 18:19   #6
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Originally Posted by hueyville View Post
Two kitchen table AR pistol uppers wandered in yesterday built to circumvent a second stamp as a real SBR. Both were having multiple issues with reliable function and taken to a guy running a gun shop out of his home. His answer was open the gas ports on both. (Daniel Defense uses an 0.083 oversize gas port so all those expensive rifles are over gassed so customers running cheap ammo don't send in as warranty issue)

Now both are having multiple over gas issues and trying to explain to owners why they need an $150ish gas block if want to run both suppressed and unsuppressed without carrying tool and remembering how many turns of a grub screw are required when snap can on or off. Both want a magic solution to gun running smoothly can on or off without making any changes. Or spending more money. Showed both the MicroMOA Govnah and the Noveske switch block and Superlative Arms as inexpensive option. The MicroMOA and Noveske builds change setting without tool but neither want to remove muzzle device, gas block, install proper block that costs what it takes to push, flip or twist and run.

Showed them several blocks where would have to l carry a Allen wrench and remember how many turns to set gas going either direction and they don't like the cheap option either. Both are breaking extractors and bolts along with having bolt over top round failure to feeds now when were short stroking before last smith opened them up. Asked if tried swapping buffers before opening ports to more blank stares. Either this new guy working on AR's must not understand implications of properly gassing and choosing buffer on a rifle that goes from suppressed to unsuppressed or like s to sell replacement parts.

Both owners said wives are a bit peeved that after buying all the parts including Geissele trigger on one, Timney on other, suppressors, wrestling with, confused, took to smith and are now having to replace broken parts. Guys have spent and spent, taken to a "gun smith" spent more and now being told that they need to spend more on a proprietary gas block and possibly a buffer swap are both overwhelmed because internet said just screw the Legos together, snap can on, snap can off, pull trigger. Imagine being over $1,500 into an unreliable AR.

Why I pin my cans and do rifle builds. Not stuck with pistol gas system and buffer trying to make an SBR. So much easier with carbine or mid length gas and rifle buffer assembly. Never broken a part even with can on and running binary mag dumps till gun was smoking. Even showed them videos of how just how hard an AR can be run and function without breaking parts. Won't be surprised to buy one or both "pistols" on the cheap as they try to recoup a few dollars to put into a factory built gun rather than try one last option.
Lol... You might tell them ... Look I have a spare Adjustable GB here.. let me RnR the GB and then if you don't like it. I'll eat the RnR , and put it back the way it was.

If they do like it and it works.. they pay for it all.

Some people, Geez .... the stories I could tell you guys from the range about "kitchen table" builds....and "customers" living in denial.
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Old December 14, 2017, 19:48   #7
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Originally Posted by bfoosh006 View Post
Lol... You might tell them ... Look I have a spare Adjustable GB here.. let me RnR the GB and then if you don't like it. I'll eat the RnR , and put it back the way it was.

If they do like it and it works.. they pay for it all.

Some people, Geez .... the stories I could tell you guys from the range about "kitchen table" builds....and "customers" living in denial.
Actually both are primed to cut losses, sell for whatever can get and buy factory built SBR or pistol not realizing that unless spend large cash for nice gun then may hit same issue when snap can on or off. Told both if whatever buy does not have something like this easily accessible to operator they will be back with similar issues but not as bad since most factory guns are usually in tolerance and specs.



I think the having to possibly adjust port size in the MicroMOA and/or swap buffers as well have them freaked about how long their woes will continue. Owner of LGS doesn't take kitchen table builds in on trade, especially ones that don't work. Hard to sell a gun that doesn't work so odds are high we will be flipping a coin to see who gets chance to make first offer to each guy as owner let's us buy guns he won't take in. Good chance nobody will want them and for right price will take them down to bare receivers and start over.

Think when I said that was only way could promise proper function they lost all their heart. They did all that work to save a few bucks and now are being told guns need a 100% disassembly, better matching of parts, checking all parts for being in spec to point of Magnafluxing the BCG's are freaked out. Have fixed a lot of AR's on table at range and have people never met mail me uppers to repair, fix for free and even pay return shipping often as a service for the community and enjoy trouble shooting rifles. Only issue is if suspect buffer or lower issues has to go to LGS since have no FFL so I can work under their license and they don't take in guns for free.

Both of these are so monkyed up am serious about breaking out my Magnaflux kit. Since both have broken multiple extractors and one broken a bolt the BCG's and barrel extensions will be coated with the nappy green powder before trust them to reuse. Have seriously considered getting my FFL and specializing in fixing table top ARs but the clientele already has flawed thinking and are upset before ever meet them at the gun, themselves and everyone on Internet that gave them bad advice. Having LGS filter them at sales level takes the personality issues out of it and just leaves fun of fixing if client is willing. Otherwise it's how I get a lot of junk box parts that become nice builds.
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Old December 14, 2017, 19:51   #8
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I din't understand any of that. Let me RnR the GB?

Anyway, the SLR is great and needed if you reload or run suppressed. If you do both, it's the only way to go. There are many adjustable gas blocks but the SLR is the one I use and recommend.
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Old December 15, 2017, 01:44   #9
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Huey, assuming the troublesome pistols are using carbine length REs, all that needs to be done is install H or H1 buffers, a quality carbine action spring, Colt or Sprinco M4 extractor springs, new extractors and an SLR adjustable gas block. Then tune the gas flow until the AR ejects but doesn't lock back. Then open the gas until it it does lock back. That's assuming the BCG doesn't leak.
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Old December 15, 2017, 05:24   #10
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And thus these guys problems. Both have been tweaking for months and sent to a back yard smith. When suggest swapping gas block, buffer spring and buffer all with checking guns for other issues the idea of pouring more money in has them upset or better yet their wives. This is common syndrom, guy builds AR, has issues leans in some discussion group and swaps parts blindy spending more money.

Finally take it to a smith of dubious skills (one took pics of smith working and was using a $7 holding fixture in $19 Harbor Freight vice) who opened up gas ports of both using a cordless hand drill and looks like he kissed the rifling on oposite side. They are bother catching flack from wife who has seen credit card bills for more money in parts than an off the shelf gun. My guess is if anyone with experience tore into either would be able to fix with parts out of their junk box.

Issue is neither of these guys mentioned owning any specialized tool other than a mag well holding fixture and combination armorers wrench. (They are friends, borrowed a punch set from third friend and shared the wrench) When asked what torque value used on barrel nut, muzzle device, etc and had blank stares. Didn't own torque wrench. Are barrels about to fall out, how large is gas port? They both want LGS to give hard and firm quote to fix. We quote hourly labor rate plus parts and they are in fear of huge bill to fight with wife over. Know guys who have never built an AR that likely could with minimal issues as have tools and use them for a living. Have other friends that can't change the oil in a 1970's pickup truck. These are in second group.

Imagine some guys modifying an FAL gas plug for suppressor and swapping gas plugs and adjusting gas every time can comes on or off? I learned wrenching on AR's with early Oly's that didn't run. Was not the anyone can screw together days and found a former Army armorer to help me initially. From what I see about half the people that order a pile of parts either need some help or a lot of help before gun runs. Kudos on them for trying but guns are funny items especially when trying to build a pistol into an SBR that will run suppressed or unsuppressed, click on, click off is a project for someone that has built a basic rifle or two or has experienced friend.

Both built pistols while waiting the year on can to clear ATF. Most trouble shooting was done months before cans cleared ATF jail then suddenly when got their stamps, installed cans entire world went sideways. Afraid these guys will get confused with any gas block that has more than three settings. Why recommended the MicroMOA though don't use myself. Figure remove existing block, measure how large port opened by guy with Dewalt hand drill, confirm buffer/spring combo then adjust size of port openings on the Govnah plate to appropriate size and they just slide into suppressed, unsuppressed or full gas if gun gets nasty. My concern is how much need to restrict gas and the Govnah gives me ability to tune as the smith but operator to not get out of adjustment later.

Neither owned an AR till tried to build a one stamp SBR on pistol. One actually ordered a handguard that was too long and his can would not screw on when arrived. He took a hack saw to his handguard as easiest solution as didnt have to remove barrel again. Just saw, turn gun, saw some more, turn gun... Hit with file and rattle can. Has all kinds of jagged points where sawed through M-Lock now, looks like teeth on a hole saw and so wrapped black electrical tape to keep from cutting hands. Wanted to take pics but they were not interested. Actually feel for these guys and if not for FFL issues would fix for free but LGS invoices if logs into book and they bought parts off internet. We help a lot if buy parts in shop.
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Old December 15, 2017, 18:17   #11
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Huey, if they are running 11.5" carbine gas barrels, port them .073" unsuppressed, .063" suppressed, H2 or H3 buffer, blue Sprinco spring and Colt or Sprinco M4 extractor spring. They won't need a third gas setting. This is very close to what I'm using with 55 gr 5.56 ammo. It makes for a good combination of soft shooting and a wide span of reliable operation.

That's assuming the BCG doesn't leak gas.
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Old December 15, 2017, 22:34   #12
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I can't assume anything with these guns. Honestly don't want to do them unless they agree to total tear down and reassembly. Letting them simmer as shop is too busy to do much than install parts bought in shop for Christmas. After the New Year see what their mindset is and offer to remove their suppressor adapters, expensive triggers and buy them out of the rest of guns so they have a down payment on a factory gun to put their suppressors on. I can tear them totally down and add parts to inventory for junk box builds. Gotta get my mind around any odd ball Kolo"rad"o rules as plan to gift a pair to friends sons who are both graduating high school a year apart. Junk box parts are good for such builds that just need a gun that runs without failure to feed/fire/extract but not big cash invested.
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