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Discussion Starter · #1 ·
So I brought my scar 17 to a gunsmith who said he couldn't remove the gas jet screw bc it was stuck. Any clue if this is common or if the gunsmith just wasn't capable or educated with it?
 

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So I brought my scar 17 to a gunsmith who said he couldn't remove the gas jet screw bc it was stuck. Any clue if this is common or if the gunsmith just wasn't capable or educated with it?
Could be either, what did he do to try and remove it? It takes heat and a modified or special screwdriver. A screw driver that is the correct size for the slot in the gas control screw to get enough “bite” usually won’t fit without grinding the sides so they’re straight and Fits through the hole in the top of the gas block. Shooting site makes a Screwdriver tool that works very well IMO. Heat is your friend, both sides of the gas block. If the slot on the gas screw gets rounded and easy out or left hand drill bit is necessary to remove it.
 

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Since the Smith said the jet was stuck, I will assume he used a slim screw driver that would fit through the hole and reach the screw head. I ground down the sides of one myself and used that. Anyway, I would suggest squirting some penetrating fluid like Kroil in there and letting it sit over night, then try it yourself. Mine came out easy without anything, but I only had a 300-400 rounds through the rifle back when I did it.
 

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Discussion Starter · #5 ·
Thanks guys I'll find some kroil, is there somewhere to buy the special tool to remove it? Dont want to screw this thing up
 

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You can buy the special screw driver. But if you have a bench grinder, I would seriously just grind down the swell part sides of an extra flat head screw driver. It only takes a few minutes. If soaking in Kroil over night doesn't work, heat up the jet with a heat gun.
 

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#1, get or make a 4mm screw driver. Because of the hole in the jet, there is not much meat left on the sides of the slot for the screwdriver to bite. If you get a poor fit, so it only makes partial contact, you can strip/round out the edges, and you are hosed.

#2, try the Kroil, but typically you need heat. Get a propane torch on the gas block till it is almost red.

#3, if you bugger it up, use a left hand 5/32 drill to drill it out. 5/32 is slightly smaller than the minor diameter of the threads, so you avoid damaging the gas block, and the friction of a drill biting has always ended up spinning the remains of the gas valve out before the drill went all the way through.

I have both screwdrivers and left hand drills on my website.
 

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Kroil..... is the way to go !!!!
Or as I would say.... CROW-OIL LOL
 
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+1 on using a drop of Anti_Seize on the threads of the new jet. I use it on automotive/motorcycle screws that take high heat. Maybe I'll take out my PMM jet and add a drop.
 

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At what round count should you remove the gas jet for cleaning and inspection for the first time? So far i have around 140 rounds through my 17. With the ranges opening again in Virginia, i will be shooting more often i hope :)
 

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I added anti seize grease to my jets. The same stuff I used on my spark plugs when I changed them. I figured if it can handle the heat that the engine and plugs generate it should be good on these doo dads.
 

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At what round count should you remove the gas jet for cleaning and inspection for the first time? So far i have around 140 rounds through my 17. With the ranges opening again in Virginia, i will be shooting more often i hope :)
The jets are not a maintenance item, once the correct gas control screw is determined and the rifle is functioning as designed you’re good to go. Anti seize as suggested by others is a good idea if changing the gas control screw again becomes necessary. Removing and reinstalling them As part of regular maintenance regime is unnecessary IMO.
 

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The jets are not a maintenance item, once the correct gas control screw is determined and the rifle is functioning as designed you’re good to go. Anti seize as suggested by others is a good idea if changing the gas control screw again becomes necessary. Removing and reinstalling them As part of regular maintenance regime is unnecessary IMO.
I pretty much agree with your comments. There is no detriment to putting a drop of anti-seize on the gas jet screw once the correct size is determined. In PMM's gas jet video, he mentions that taking the rifle from your home location to another location with a drastically different altitude may have an effect on the cycling with a particular jet. Some people actually travel with their rifles to other states for training and/or hunting, so there may occasionally be a need for them to swap a jet +/- one size. My rifle is tuned to a 1.35m jet, and I doubt I will ever need to swap it, but I keep a 1.40mm jet in my range bag anyway with a small hex wrench. It would have been a plus if the Scar had three gas settings: Regular Adverse and Suppressor. But I guess they felt over-gassing it a bit was the best solution. After someone mentioning anti-seize in this thread, I went ahead and added a drop to the jet and cleaned up the whole gas regulator area while I was at it.
 
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Thanks for the info guys. I will at least remove the jet and add some anti seize to it, just in case in the future i want to change it out.
 

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Hot, high pressure (12,000 PSI) gasses at the end of the muzzle will erode the gas jet, causing it to grow over time. So occasional replacement is warranted. Question is what round count.

The throat of the barrel will also erode. Match grade barrels are maybe 5,000 rounds, but that is 50-60,000 PSI. Chrome lined are 10,000+. Percussion nipples in muzzle loaders will erode with 25,000 PSI chamber pressures, though I forget their lifespan. Net, it is almost certainly in the range of multiple thousands. Replacing it as you replace a barrel is probably a good idea.
 

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Kroil & anti-seize will become your SCAR's best friends...
 

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Is the consensus that a LH 5/32" drill bit would be able to extract a stuck factory screw as well as applying heat to the gas block? How much heat is realistically recommended?
Also, I test fit a 5/32" bit and it seems there's minimal room for error. Could I use a slightly smaller LH drill bit?
 

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what screw...the gas jet? if you need to heat it... vid from PMM, states heat it until gas block is rosacea colored
kroil has worked for others w/o heat

& use the proper gas jet tool, not a drill bit.... or grind down the sides of one of your screwdrivers.
i havent read anyone needed to use an extractor bit to remove gas jet
 
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