Adjustable gas block - HELP!

[b4uqzme]

Well I thought I'd be smart and intall an Ergo adjustable gas block on my first AR build. The gun shoots great but the bolt will not cycle enough to eject the round or hold the bolt open. Only two rounds out of thirty cycled properly and those two ejected cases were noticeably hot to touch. All the others were just lukewarm. It appears to have a gas leak at the gas block adjustment screw. Was I supposed to put some kind of thread sealer on there? Do you think I'm looking in the right area? Any advice appreciated. Thanks. :confused:

[RRP]

It appears to have a gas leak at the gas block adjustment screw. Was I supposed to put some kind of thread sealer on there? Do you think I'm looking in the right area? Any advice appreciated. Thanks. :confused:

No thread-locking compound is needed on the gas adjustment screw of the Ergo gas block. Instead, the adjustment screw is locked into place with an opposing set-screw.

If you have insufficient gas to operate the action, it's possible the gas block is not correctly aligned on the barrel. That would be the first thing to verify.

[b4uqzme]

I guess I wasn't thinking about thread "locker" (it's an adjustment screw) but there definitely is a leak there. Is that normal? Would a thread sealer be in order or would that just gum things up?

And thank you. I did check the gas block alignment and noticed that I missed something the first time. There is an indent in the bottom of the barrel. I assume that is for one of the two set screws. Aligning to that indent moves the block forward about 1/32. Would that be enough to make a difference? And why is there an indent anyway? Lots of gas blocks mount differently. How did they know which one I would buy? I guess the real question: what's the process to assure it's aligned correctly?

Thanks again. Everything else is working great.

[CJB]

Leak at the gas screw.

Do you have the slightest idea about how your first build AR functions? What is the distance from the chamber to gas port, then to the muzzle? What is the size of the gas port in the barrel. What is the weight of the recoil spring. Weight and element configuration of the buffer? What is the size of the gas tube vs the bolt carrier key? How about the fit of the carrier and bolt?

There is so much to this, it aint even funny. You cannot just slap some stuff together and expect perfection, unless - you go fully with certified GI spec parts. I'm sounding like a AR snob, but I'm not. The crap has got to all work together. The AR is not like an M14 or FAL with its self metering gas system. The AR's demand on consistent pressure at the carrier is far greater then most designs.

[b4uqzme]

Understood. So teach me CJB-san. And I'm still curious. Why should gas leak from the adjustment screw? Is that a fatal flaw?
What can be done about it?

[CJB]

Will comment after i get back to a keybd.

[b4uqzme]

Thanks. Meanwhile I will take it apart and triple check the stuff that you and RRP mentioned. The intertube seems to think gas block location is the typical issue. So I will quadruple check that. Then check for obstructions, buffer weight, etc. I wouldn't have complained if it had just slapped together and worked perfectly. But how else will I learn?

[Bawanna]

You didn't complain, you merely brought forth an issue to be addressed by those who have slapped them together and experienced defeat before you.
They aren't smarter than you, just not quite as dumb as you at this moment.
Hopefully in the next day or two you won't be dumb at all when it comes to adjustable gas blocks and I'll be the last remaining dumb head when it comes to adjustable gas blocks.

[gb6491]

Well I thought I'd be smart and intall an Ergo adjustable gas block on my first AR build. The gun shoots great but the bolt will not cycle enough to eject the round or hold the bolt open. Only two rounds out of thirty cycled properly and those two ejected cases were noticeably hot to touch. All the others were just lukewarm. It appears to have a gas leak at the gas block adjustment screw. Was I supposed to put some kind of thread sealer on there? Do you think I'm looking in the right area? Any advice appreciated. Thanks. :confused:
I'm no AR guru (don't really mess with them that much), but that much difference in temperature between the cases that cycled properly and those that didn't would make me suspect the ammo some.
Regards,
Greg

[Bills1873]

I'll buy one already completely assembled by someone smarter than me!

[b4uqzme]

I'm no AR guru (don't really mess with them that much), but that much difference in temperature between the cases that cycled properly and those that didn't would make me suspect the ammo some.
Regards,
Greg

Remington UMC. I gotta a couple boxes of Federal and PMC. I'll put them on the list of potential fixes. Thanks.

[b4uqzme]

I'll buy one already completely assembled by someone smarter than me!

Nooooo. That's the last thing I want: to discourage someone from trying themselves. Researching and building it was an education and a lot of fun. But I've yet more to learn. And I'm confident it will be up and running soon. Just sharing my experiences so 1) I can learn from others and 2) others can learn from my experiences.

[muggsy]

You could try reading. It works every time its tried.

[CJB]

Ok, back at a keyboard.

Sorry to make it seem like I was berating the OP, I am not. But, do admit I was too strong. My apology.

Ok, zero, zilch, nada details about the components used, so here goes.

#1. Sure, fix the leak. It would have to be a sizable leak to prohibit functioning, but it needs fixing.

#2. Maybe before you do that... make sure the barrel port is clear, and

#3. Make sure the corresponding area on the gas block are in the same spot. They can vary. Especially if you have to cross drill the barrel yourself, or the block is only held by a set screw. If the body of the block partially obscures the barrel port, then expect issues.

#4. Make sure you have the correct buffer. There are at at least four common types and a few manufacturer specific types too. Too many disks, too much weight, wrong stuff, it wont work.

#5. Make sure the carrier key id and the gas tube OD are compatible. Mismatch can result in as much as .012 difference. Carriers run from about .175 to .190 inside. Tubes run from about .172 to .188. Sloppy fit there, not good. I'm not sure on the spec, but know that cheapo parts and knock off parts, etc etc, have some issues there. Same with the alignment of the ports as in #3... lots of variation.

#6. Port diameter.... hard to measure, but... using guitar strings (or wire gauges) you can approximate the ID. These run from about .062 to about .085ish! Huge difference. Long barrels have larger ports if the gas block is further from the chamber.

#7. Port diameter for an adjustable block should be on the plus side of things, so it CAN be adjusted. The adjuster can only decrease gas flow, so you need more gas in order to actually be able to throttle it (and open it if needed).

Thats my 2c on the whole thing. Its like trying to buy a bunch of 1911 parts that are "drop in" and expect it all to work. It can, or... maybe not, especially in the fire control parts. With so many aftermarket parts and such, and so many makers feeding a crazed market, there are so many variables.

More specifics would be helpful.

[b4uqzme]

Thanks. Off to work I go.

[b4uqzme]

... Aligning to that indent moves the block forward about 1/32. Would that be enough to make a difference? ...

^^^ Yep! Thanks RRP. And thank you all for getting me pointed in the right direction. CJB your list is a great help. And yes muggsy I am reading all I can find. It's still not 100%. Bolt will not hold open no matter where I adjust the block. So I am off to research buffers and springs plus figure out a good way to measure that barrel port. All my guitar strings are on guitars. I'll ask if I get stuck again.

Great learning experience = fun and worthwhile. Way better than just buying something and shooting it. Even with the hiccups. Thanks!

p.s. Note to other newbie builders. Don't fully install your muzzle device until after you are assured the gas system works right. No big deal...just a waste of a crush washer.

[CJB]

may I assume the bolt holds open when manually withdrawn?

[b4uqzme]

may I assume the bolt holds open when manually withdrawn?

Yes. With authority and with 2 different brand mags. Thanks. I'm researching to see if there is still too little gas to fully open the bolt (I would have to either replace the gas block or enlarge the barrel port. The latter is something I really don't want to do.) I'm learning that the bolt can cycle too fast for the hold open to catch and that sometimes a heavier buffer can cure that. It's an innocent thing to try. Just a little money for a couple different buffers. I need to weigh it to confirm but I believe I have a carbine buffer. The spring is definitely a carbine spring = 36 coils. Both the buffer and the spring came with a mil spec carbine tube I bought as a kit. The buffer is aluminum and appears to be of acceptable quality.

Other stuff:
16 inch AR Stoner SS barrel in .223 Wylde. 1/8 twist. Port is 6.5 inches from the end of the barrel. Mid length gas system.
Crosshill Technologies side charger upper and BCG. Gas key is secure and staked.
Generic mid length gas tube. .180 outer dia at the flange that mates with the key. Good fit with the key.
What else? Hmmm. Need to check CJB's list.

I learned a lot about lubrication. I think that plus getting the gas block aligned correctly was my ejection fix. Correcting the gas leak didn't hurt but I don't think it was big enough to be the issue. We are close.


These ARs are not too complicated but CJB is right...not all parts will work together as a team. Thanks so much again. Lemme know if I am on the right track.

[b4uqzme]

^^^ Oh. And I've tried several types of ammo. Wolf, Tula, PMC, Federal, Remington, American Eagle. But all just 50 or 55 grain. They all eject fine. The 50 grain Federal requires I open the gas block one more full turn. Ammo ejects to 4:00 when the block is adjusted right. I'm still not sure how ammo choice affects this whole thing other than quality ammo is good. That's something I am learning too.

p.s. Those two "hot" Remington rounds that cycled before were the outliers. And a little scary now that I think about it. Seems they were overcharged? I don't think I'll be shooting any more of that.

[CJB]

you wont need a heavier buffer, just throttle your gas block

[b4uqzme]

you wont need a heavier buffer, just throttle your gas block

By throttle I think you mean to decrease the gas flow? So far that's not consistent with my trials. I can throttle it back from wide open to the point where it will not eject and never get the bolt to hold open. Hmmm.

If by throttle you mean open it more, I have already tried way past the block's full capacity. IF I have it aligned right finally and I think I do, then I have to replace the block or the tube or open the barrel port or ???

[CJB]

With what you did, its not over cycling.

[CJB]

Also....gotta measure the port. And how about a list of components you used?

[b4uqzme]

Thanks CJB for your interest and experience. I probably won't get to fiddle with this again until the weekend. Maybe find a drill bit to fit the gas port then measure that. Meanwhile, here's a list of components:

B4-AR BUILD.1 4/20/2016
AR-15 Anderson lower – basic 7075-T6 forged 1
2/2/4457 CROSSHILL TECH RIGHT SIDE-CHARGING UPPER RECEIVER ASSEMBLY 1
RA-140 Rise Armament RA-140-SST Super Sporting Trigger 1
Nordic Components Slotted C... Nordic Components Slotted Customizable Free Float Tube Handguard AR-15 Mid Length Aluminum Black 1
ERGO Adjustable Low Profile... ERGO Adjustable Low Profile Gas Block AR-15, LR-308 Standard Barrel .750" Inside Diameter Steel Melonite 1
AR-Stoner Barrel AR-15 223 ... AR-Stoner Barrel AR-15 223 Remington (Wylde) Medium Contour 1 in 8" Twist 16" Fluted Stainless Steel 1
CMC-91401 CMC Anti-Walk Pin Kit-Set of (2) .154 pins for AR15 Hammer & Trigger 1
MAG-417-BLACK Magpul MOE Enhanced Polymer Trigger Guard - Black - MAG417BLK 1
JB-LPK-LTG JBO Lower Receiver Parts Kit WITHOUT Trigger Parts 1
MAG-400-BLACK MAGPUL MOE Mil-Spec Carbine Stock - Black - MAG400BLK 1
JB-MilSpecKit Mil Spec 6 position Stock Hardware Kit-AR15-USA Made 1
JB-GasTube-MIDLENGTH JBO Stainless Steel Gas Tube - Mid Length 1
RRA-AR0001A2 Rock River Arms -A2 Flash Hider, .223 1
YHM-28-5CW YHM Crush Washer for flash suppressor 1

[CJB]

A .0625 drill should fit in the hole on a 16 inch barrel. Thats 1/16 inch. A 20 inch full length should be 3/32 or .0925

[CJB]

Drilling the hole larger is easy. Put a close fit rod in the bore and go slow.

[b4uqzme]

Thanks. The 1/16 fits...a little loose. The next size I have is 0.0755 and is too large. Do you recommend that?

[Bawanna]

I'm no authority by a long stretch on this gas port thing but I compare drilling gas ports to fooling with mother nature.

I know the instructor at Colt Armorer school was highly against it.

He had a fella bring one in that would slap the crap out of his finger everytime he shot. He looked it all over couldn't find anything so he shot it and it slapped his finger sooooo bad. He almost cried and he's one big tough cookie too.

He looked it over some more and like a dumb head thought it was just a fluke so he tried it again, and of course got his finger slammed again.

Turned out the guy had thought if a little gas was good, a little more or a lot of gas would be better. Guess he was wrong.

[CJB]

Before altering, try a standard gas block.

[b4uqzme]

Ok thanks.

[b4uqzme]

Thanks. The 1/16 fits...a little loose. The next size I have is 0.0755 and is too large. Do you recommend that?

0.0755 did it. Thanks again for your guidance.

[CJB]

There ya go! You can always throttle it back a bit with your adjustable block, if need be.

[CJB]

I'm no authority by a long stretch on this gas port thing but I compare drilling gas ports to fooling with mother nature.

I know the instructor at Colt Armorer school was highly against it.

He had a fella bring one in that would slap the crap out of his finger everytime he shot. He looked it all over couldn't find anything so he shot it and it slapped his finger sooooo bad. He almost cried and he's one big tough cookie too.

He looked it over some more and like a dumb head thought it was just a fluke so he tried it again, and of course got his finger slammed again.

Turned out the guy had thought if a little gas was good, a little more or a lot of gas would be better. Guess he was wrong.

I can imagine that the COLT armorer would be dead set against making the port bigger. Reason being is that Colt has worked out the sizes for their barrels and gas blocks, and bolt carriers and bolts and buffers and springs, and etc etc.

When you start from a mix-n-match bundle of parts in a crate, its not hard to imagine that some tweaking might be needed. What the tweaking is, and how much... that's the rub.

[Bawanna]

He was devout Colt and discouraged any mixing and matching for sure.

He was a sharp cookie though. He wrote his own armorer manuals and they were his, not Colts.

Good guy, really knows his stuff.

[CJB]

Yah, and imagine.... tryin' to keep track of all the ins and outs of all the stuff out there. In the "craze" of AR, there are some fine parts, and there is some real crapola stuff too. Sort of like, 2 bit shops saying, we got a load of 16 inch barrels, lets just cut 'em and recrown 'em, and sell 'em as 10's, 12's and 14's. Or, the "receiver extension" (recoil spring/buffer tube): Mil size, commercial size, and then a few oddball "off brand made in the far east sizes". Colt makes good stuff yet as far as AR's go. FN does. Folks rave about BCM, but I'm not impressed with their upper I have. Its not bad, just not "wow", and has the same casting house marks as my recent Colt AR (Keyhole/Cerro Forge). And, for that matter, the Noveske upper has the same mark too, so they all started out life in the same place. Of those, the Noveske is the nicest, but the price on those is pretty dear these days now that John Noveske has passed on.

All I'm sayin' is there are good parts, which actually meet the prescribed military spec. Then there are parts which "claim" to meet spec (and may meet some of the specs for that part). Then there are those that say Mil Spec only because they "fit" into/onto mil Spec parts. Go figure! The bolt carrier fits into an upper, so its Mil Spec! I think not!!!

Thats why I keep my Wham-O slingshot armorer's certification. Its easy!

[GROTMAN]

Hope all your problems are solved... now I kind of got one.. :p
https://66.media.tumblr.com/476920a7c80ecb35743718a64f43d6d2/tumblr_nqbql9tHwP1r94kvzo1_400.gif

fyi.. no that's not really me :biggrin1:

[b4uqzme]

^^^ nice tatts.