Adjustable gas block - HELP!

[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