SBR AR15 is jamming - HELP ME

[44 MAGNUM SHOOTER]

If it isn't locking open, you are short stroking for some reason. It could be not enough gas OR too much gas causing hard extraction due to timing issues.

Are the rims of the cases chewed up where the extractor grabs them and are there smear marks from the ejector on the headstamp? Going to a heavier buffer usually helps if you are overgassed, so it may be a gas port size problem. Have you checked to make sure your FSB isn't canted at all?

Best,

Joe

the spent cases seem fine, no wierd marks that i can see..

I am going to really check to make sure the FSB is as straight as possible.

 

[44 MAGNUM SHOOTER]

It is a under gas issue, have you tried other ammo?

yes sir, bother xm193 and remington .223

 

[shooter521]

gas block is attatched by screws - it's a yankee hill 4 rail

gas key is not staked

Check the alignment and tightness of the gas block; stake or rocksett the screws.

Check the tightness of the gas key screws; stake them (they should have been staked at the factory).

Also check the bolt gas rings if you haven't already. And I mean a visual inspection, not just the stand-up test described earlier.

 

[wally05]

Check the alignment and tightness of the gas block; stake or rocksett the screws.

Check the tightness of the gas key screws; stake them (they should have been staked at the factory).

Also check the bolt gas rings if you haven't already. And I mean a visual inspection, not just the stand-up test described earlier.

+1. Definitely check that gas key.

 

[44 MAGNUM SHOOTER]

+1. Definitely check that gas key.

The gas key bolts are tight but plan to have them staked just for piece of mind

 

[wally05]

Get us pictures of a lot of this stuff if you can. It sounds to me like a gas flow issues. So, like shooter said, visually check a lot of this stuff. What kind of buffer are you running that SBR?

 

[E5RANGER375]

Never push anything into the gas tube. The gas tube is closed on one end and you will push junk into the gas port. New gas tubes are cheaper than creating a single shot.

never had a problem yet, with the Hundreds of M16's, M4's, AR's, etc.... combined that ive used and worked with over the years in every environment around the world. to each their own i guess. no its not something you do or need to do often, but properly done its ok. sometimes gas tubes arent easily aquired also if he takes off the gas tube then whats he pushing debris into??

 

[sporter]

I would try process of elimination:

1. Swap bolt and carrier for another. If it still fails then you know it's not that causing the problem.
2. Thoroughly clean the rifle, bolt group, chamber etc.

Obviously it is short stroking but and common sense says it is a gas problem but there are other things that could delay operation of the action or parasite power away from the action cycling.

1. Check for gas tube alignment to carrier gas port (make sure it is not "catching")
2. Inspect for burrs in chamber. Is chamber chrome lined? (might want to polish chamber up a bit if it is not chrome lined with some steel wool and light polish.
3. Try different ammo (however I am not a big fan of a rifles that will only run on 1 type of ammo)
4. Grease! The bolt and barrel extension might take a bit of time to mate to one another and sometimes some grease on the bolt lugs can aid in the break-in process.

Good luck..

 

[Cpt Caveman]

How can the gas tube be closed on one end if gas is going through it? I've never been told to "Never push anything into the gas tube."

 

[E5RANGER375]

How can the gas tube be closed on one end if gas is going through it? I've never been told to "Never push anything into the gas tube."

its flawed reasoning. im no civilian "certified" gun smith, but ive worked on and fired these for a living and to stay alive for the last ummmmm 12 years. not as long as some, but some dont use them almost EVERYDAY. i think my military training is pretty good. no im sure im not "the best" but im not less than advanced either

 

[shooter521]

How can the gas tube be closed on one end if gas is going through it? I've never been told to "Never push anything into the gas tube."

The front (muzzle) end of the gas tube is closed; the gas port is on the bottom surface a fraction of an inch back. The back end, where the tube protrudes into the upper receiver and interfaces with the carrier key, is open.

When I went through armorer's school, we were taught not to insert anything into the gas tube in order to "clean" it, since this can in fact cause fouling to pack into the closed (forward) end of the tube and possibly occlude the gas port. Additionally, pipe cleaners can break down and shed, introducing more debris into the tube. Finally, given the design of the tube, you can't really see in it to ensure that it is clean, anyway.

I have never cleaned the gas tube on any of my ARs, and have never had an issue.

i think my military training is pretty good.

Undoubtedly, but it's not necessarily reflective of current thinking (given that the military is a large beast and can be slow to change/update it's TTPs), nor is the military way the "only" way that works.

My

 

[j706]

The front (muzzle) end of the gas tube is closed; the gas port is on the bottom surface a fraction of an inch back. The back end, where the tube protrudes into the upper receiver and interfaces with the carrier key, is open.

When I went through armorer's school, we were taught not to insert anything into the gas tube in order to "clean" it, since you can in fact cause fouling to pack into the closed (forward) end of the tube and possibly occlude the gas port. Additionally, pipe cleaners can break down and shed, introducing more debris into the tube.

I have never cleaned the gas tube on any of my ARs, and have never had an issue.

Correct!!

 

[44 MAGNUM SHOOTER]

Get us pictures of a lot of this stuff if you can. It sounds to me like a gas flow issues. So, like shooter said, visually check a lot of this stuff. What kind of buffer are you running that SBR?

Spikes ST-2T Buffer. Will post more pics when i can

 

[E5RANGER375]

thats why you take the tube off to clean it. just like the key.

 

[jeremy]

Gas tube would be the first thing I would look to with these symptoms...

Either run some Carb and Choke Cleaner through it or Simple Green and hot water... Either does a great job of stripping Carbon out of the tube. Make sure to run a light coat of oil across the gun after words though. Due to the fact they also do a great job of pulling the oil off also.

This should fix the problem.

Don't have to take the tube off this way to clean it either...

 

[E5RANGER375]

Gas tube would be the first thing I would look to with these symptoms...

Either run some Carb and Choke Cleaner through it or Simple Green and hot water... Either does a great job of stripping Carbon out of the tube. Make sure to run a light coat of oil across the gun after words though. Due to the fact they also do a great job of pulling the oil off also.

This should fix the problem.

Don't have to take the tube off this way to clean it either...

simple green is the shiznit!!!

 

[pftraining_in]

thats why you take the tube off to clean it. just like the key.

You remove the gas key for cleaning? Were you taught this or is this something you do on your own?

Us under trained civilian armorers are taught to only remove a gas key that is damage as multiple staking attempts will damage the material of the key and cause damage to the charging handle and weaken the material. If a gas key is removed it should be replaced with a new key.

never had a problem yet, with the Hundreds of M16's, M4's, AR's, etc.... combined that ive used and worked with over the years in every environment around the world. to each their own i guess. no its not something you do or need to do often, but properly done its ok. sometimes gas tubes arent easily aquired also if he takes off the gas tube then whats he pushing debris into??

Please share your knowledge as to how removing the gas tube stops debris from being pushed into the muzzle end of the tube?

When not in third world countries, gas tubes can be purchased at the following locations for under $20.

Bravo Company USA, Inc. AR-15, M16, M4 Tactical Gear, Parts, Accessories.

HIGH STANDARD : GAS TUBE, 16" - World's Largest Supplier of Firearm Accessories, Gun Parts and Gunsmithing Tools

https://www.gandrtactical.com/cgi-b...te=PDGCommTemplates/FullNav/SearchResult.html

Rock River Arms: Barrel Assembly Parts

 

[E5RANGER375]

You remove the gas key for cleaning? Were you taught this or is this something you do on your own?

Us under trained civilian armorers are taught to only remove a gas key that is damage as multiple staking attempts will damage the material of the key and cause damage to the charging handle and weaken the material. If a gas key is removed it should be replaced with a new key.



Please share your knowledge as to how removing the gas tube stops debris from being pushed into the muzzle end of the tube?

When not in third world countries, gas tubes can be purchased at the following locations for under $20.

Bravo Company USA, Inc. AR-15, M16, M4 Tactical Gear, Parts, Accessories.

HIGH STANDARD : GAS TUBE, 16" - World's Largest Supplier of Firearm Accessories, Gun Parts and Gunsmithing Tools

https://www.gandrtactical.com/cgi-bin/commerce.cgi?preadd=action&key=GRT-GT&reference=/cgi-bin/commerce.cgi%3Fsearch%3Daction%26keywords%3Dgas%20tubes%26searchstart%3D0%26template%3DPDGCommTemplates/FullNav/SearchResult.html

Rock River Arms: Barrel Assembly Parts

if a gas key is buggared up i replace it. i dont remove it for normal cleaning. we arent talking about a normal cleaning here. no i dont tear down the entire gun everytime clean., AR's dont require too much in depth maintenance once you get them shooting. this is (most likely) a preasure issue so id be going through a process of ilimination. including checking to make sure that barrel is torqued correctly (thats number one thing id do after cleaning). yes i would replace the key and the tube as long as i had them availible of coarse, if i thorough cleaning didnt work first. ive been through civilian classes too and they arent far off from what the military teaches in advanced training.

you and i probly dont do much different truethfully, except i dont mind putting something in the gas tube to clear it. but i also make sure afterwards its free of debris.

typing about what id do without the rifle in front of me is a lot different than having it in my hands. sometimes you can look at wear or the fuction first hand and know exactly whats going on. a forum diagnosis isnt the best, thats why i offered to see it first hand.

 

[mvician]

It came with a 10.5 originally but I replaced it with a wilson 11.5 heavy barrel and it ran fine last year. I will try an you suggest

What changed since last year when it ran fine?

 

[jeremy]

Sitting in a safe letting happen what only time can do...