Adjustable gas block seizes up

T

tangolima

New member
After a few hundred rounds, I can't adjust the screw anymore. Pretty seized up. Penetrating oil overnight hasn't helped yet. More oil and time? Maybe heat?

I guess I need to drop clp into the threads and move the screw every now and then to keep it from seizing up. How about high-temp grease on the threads?

-TL

Sent from my SM-N960U using Tapatalk
 
Last edited:
What kind of block is it? Some are adjustable--some are bleed-off and some are a combination of both. I find that generally my problems are the opposite; that there is a general tendency for the adjustment screws to come loose and drift, especially if I change the settings frequently. Sometimes a lock screw can simply fall out or fail to do anything more if the port flow is beyond full-open. Are you seeing any indications of gas escaping? This could possibly be an over-pressure sign from the port. Depending how the port is aligned and finished (I've seen lots of them that were poorly executed) it's not unusual for accelerated erosion to occur as the bullet goes ripping by and deformed edges turbulate the gases and mix with residue and pieces of metal. That stuff gets jetted into the block and tube. Might be worth a look with a borescope if you can.
 
It is the most primitive shut-off type. A screw jams into the orifice to pinch off the gas. I guess hot gas sips into the threads. Residue and corrosion caused by high temperature seizes the threads up.

-TL

Sent from my SM-N960U using Tapatalk
 
Did some research online. Looks like it happens quite regularly. To unlock, it is similar to seized up screw. Penetrating oil, time, and finally heat from propane torch. Moving the screw every now and then helps. But it may not be practical in some guns. It is a hassle to remove the handguard to get to it.

I'm going to try that recipe to unlock mine. After that I'm going to try the anti-seize compound for spark plug.

-TL

Sent from my SM-N960U using Tapatalk
 
Good post. I would have Kroiled it, waited 24 hours and if it didn't budge, heat it. How about grease before rescrewing it down?
 
Grease needs to survive the high temperature. I have a tub of high-temp grease. The anti-seize compound for spark plug in a car may work. Will try all that.

-TL

Sent from my SM-N960U using Tapatalk
 
Ok had one fixed. The trick is to apply a few drops of clp to the screws before going to range. A course of firing created heat and shock. The screws came loose afterwards with some struggling.

Then I applied anti seize lube to the screws after cleaning carbon deposits. It is the same type of anti seize for spark plugs in cars. Good for temperature up to 1000C. But still I will get into habbit of "exercising" the screws whenever possible.

One fixed, another one to go. This one could be trickier. It has smaller screws. Stripping the screw head is more of a risk.

-TL

Sent from my SM-N960U using Tapatalk
 
Last edited:
stagpanther said:
Solution is simple--get a Superlative Arms adjustable gas block.
Click to expand...
I may. Actually I looked into superlative. Didn't go for it as it is a bleed off type. At the time I was experimenting something that required a pure cut-off.

It isn't bad if the anti seize works. But for sure I need to stay away from the super low profile type that uses tiny screws, unless I plan to never readjust.

-TL

Sent from my SM-N960U using Tapatalk
 
tangolima said:
It isn't bad if the anti seize works. But for sure I need to stay away from the super low profile type that uses tiny screws, unless I plan to never readjust.
Click to expand...

But it won't work. AND, the gas will cut the screw putting metal into your bolt carrier group and eventually open up to full anyway.

I've designed a few gas blocks, used a LOT more and for me, it is no adjustment or Superlative Arms. That's it, full stop.
 
Torch it. That is the only way to really break the carbon free after trying penetrating oil and such and without strong arming the tiny parts into contorted submission.

Originally Posted by stagpanther
Solution is simple--get a Superlative Arms adjustable gas block.
Click to expand...

I have 3. All are seized.
 
MarkCO said:
But it won't work. AND, the gas will cut the screw putting metal into your bolt carrier group and eventually open up to full anyway.



I've designed a few gas blocks, used a LOT more and for me, it is no adjustment or Superlative Arms. That's it, full stop.
Click to expand...
I'll see about that. Based on what I read, even superlative may not be a full stop big enough. :)

I'm waiting for a couple of new gas blocks to arrive. Once I get those, I will go full tilt on the other stuck gas block.

I'm not ejection pattern obsessive. It is quite easy for me to say "it works". I actually don't need adjustable gas blocks. I was experimenting something that required cut-off adjustable. After that I went "why not" and bought the super low-profile with tiny screws.

-TL

Sent from my SM-N960U using Tapatalk
 
Does that screw act like an adjustable needle valve, and in this case, allow a percentage of gas to bleed by it, based on adjustment?
Doug Lee
*
 
Doug Lee said:
Does that screw act like an adjustable needle valve, and in this case, allow a percentage of gas to bleed by it, based on adjustment?
Doug Lee
*
Click to expand...
It is the most basic cut-off type without bleeding off. The screw threads into the gas orifice to regulate the flow.

There are two screws; the main screw that threads into the gas orifice, and the lock screw that locks the main screw in place. In the normal design, the main screw is short, and goes in sideways. The lock screw is long and goes in straight. This super low profile does it the other way around. The main screw is a long one that goes in straight.

-TL

Sent from my SM-N960U using Tapatalk
 
Ok. Submerging in penetrating oil for a couple days did nothing. Finally some propane torch action adjusted the bad attitude.

The screws are #4-40 black oxide set screws. Size is small but serviceable. I will replace the main screw with normal stainless steel socket head to avoid the weak 0.05” Allen key. With anti seize applied to the threads, it should do better. I probably will drill and tap the secondary screw hole to #6-32 so that use the same size of Allen key to adjust both.

The anti seize helps quite a bit in other adjustable blocks. Adjustment hasn't been that smooth. Round count is still low. We will see in a few more months. So far it seems a right way to go.

-TL

Sent from my SM-N960U using Tapatalk
 
Last edited:
You could try some Alloy 330 screws if they come in your size. It is rated to 2100°F oxidation resistance, and the silicone content is supposed to resist carbonization.

Years ago, I bought a can of Bostik Pure Nickel Never-seez, a nuclear reactor fitting-rated anti-seize, and I have used it on barrels ever since. Rated to 2400°F.
 
McMaster sells super corrosion resistant screw for a small sum. It is probably an overkill. Anything stainless steel is better than the original black oxide screw.

For anti seize I got this one for cheap.Permatex 81343 Anti-Seize Lubricant, 1 oz. Tube , White https://a.co/d/4xNoO6d

I think it is aluminum loaded. 1600F rated. Probably good enough.

-TL

Sent from my SM-N960U using Tapatalk
 
That anti-seize is a mix of aluminum, copper, and graphite. There is also just copper and graphite anti-seizes available that is rated at 1800°F, and then there is the nickel and graphite one I mentioned are rated at 2100°F. How often one actually gets to higher temperatures for long enough to matter, I can't say. If you assume 4500°F to 5000°F powder combustion temperature at peak pressure and that it drops to around a third to a half of peak pressure at the gas port, it might still be in the 2000°F range, albeit briefly.

For carbon, if Slip2000 Carbon Killer seems too harsh, Gunzilla will penetrate and soften carbon, albeit more slowly. I once had it remove all the hard carbon and rust from a pitted bore, causing both to just fall out of the pits and leave them bright steel-colored. But it was sitting for about six weeks. I've also had it soften carbon rings at the end of a chamber in about 24 hours. None of the other penetrating oils or other gun cleaners have done that for me.

Another recommendation I've seen is a long soak in Mobil One motor oil, which has carbon cleaning agents in it, too. But I find it works better on new, warm carbon than on cooled and hardened stuff. But if you have some or if you want to try it in place of the anti-seize, it might keep carbon down if it isn't blown out of position.
 
You must log in or register to reply here.
Back
Top