New SBR build. FTEject. Need help.

waepek

waepek

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Recently build a 10" AR with the ff: parts.
Aero Precision Lower
Stag LPK w/ Noveske Trigger
VLTOR Vis-2AK Upper
ATRS 10" Barrel with Pistol length gas port.
AAC Muzzle Brake

Tried Saturday and had about 8rds out of 250 fired that failed to eject and encountered trigger slap. Most of the cases ejected around 1-1:30 o'clock area. Someone suggested lighter buffer spring if that makes any sense which I don't have a clue where to get. Researched online and came up with an overgassed system. Will a heavier buffer and buffer spring help?? Adjustable gas block maybe??
Thanks
 
Sometimes a heavier buffer weight helps solve a lot of the cycling issues with short rifles, usually a Spikes Tactical T2 buffer does the trick. I think there are lots of suggestions on previous posts. And that's usually the end solution.
 
Why do you have a pistol length gas port on a carbine length barrel? Wanna hazard a guess as to where the overgassing is coming from?

Your only choice is to go with an adjustable gas block and try to reduce the massive amount of pressure going into the recoil system. A heavy, read VERY heavy buffer may help as well.

The trigger slap is a result of extremely high BCG velocity. Which if not corrected is gonna beat the gun to death.

And finally there is no such thing as an SBR in Canada. That is a uniquely American classification due to a stupid law.
 
Currently using a standard buffer and buffer spring. Ordered T2 and T3 buffers along with an extra "power" spring. Hopefully it'll work. Next would be an adjustable gas block.

Saputin I picked up the barrel from the EE. It is made by ATRS and came with a pistol length gas port. I figured they make and sell barrels so it should be fine??
 
You are correct with "they make and sell barrels so it should be fine" but miss the part about a gas operated AR is a fine balance between gas pressure, recoil spring tension, BCG weight, and buffer weight. You can't just throw any combination together and expect it to work reliably.

I would contact ATRS and ask them what setup they suggest for what you have.
I am sure they can tell you exactly what you need to make it function 100%.

Good luck.
 
I did just that CR5. Called ATRS and was told that the system might be "undergassed" and to try a lighter spring. OR redrill the gas port which is around .086" to .090" . I thought if there are any issues of undergassed system the bolt will not lock back after last round. From what I gather online the shorter the barrel the closer the gas port is to the chamber and the sooner the bolt functions and at a higher pressure causing ftes and it is overgassed. Now I'm confused. =o(

FWIW the rifle doesn't have any problem with the bolt locking back after last round.
 
to me. it sounds like your ar is overgassed...i would definitely try a heavier buffer or spring first.

did you grab any ejected brass? check for any mangled casings to help support this theory.

i've had problems going the other direction (undergassed)...what i found is that the round would fire and eject but thats it, every other round my trigger would not return to firing position, it also failed to lock back on the last round sometimes as well.

i had to lighten the spring significantly for the thing to cycle properly. after that its been running like a sewing machine.
 
I see in another thread a post by the OP talking about this carbine being a 300 BLK. It would have been helpful to this discussion if you'd noted that in the first place because a 10" 223 barrel with a pistol length gas system makes NO sense. However it makes perfect sense in a 300 BLK and it makes this discussion a bit more complicated.

Trigger slap is def a sign of over gassing but the most common cycling issue with 300 BLK is undergassing. You have not specified what ammo you were using. Subsonic, supersonic, handloads or factory? All of that will make a big difference.
 
waepek said:
I did just that CR5. Called ATRS and was told that the system might be "undergassed" and to try a lighter spring. OR redrill the gas port which is around .086" to .090" . I thought if there are any issues of undergassed system the bolt will not lock back after last round. From what I gather online the shorter the barrel the closer the gas port is to the chamber and the sooner the bolt functions and at a higher pressure causing ftes and it is overgassed. Now I'm confused. =o(

FWIW the rifle doesn't have any problem with the bolt locking back after last round.
Click to expand...


Ya, that advice sounds completely opposite of what I expected them to tell you.
Hopefully the heavier buffer and spring you ordered will bring it back into balance.
If not there was an adjustable gas block on the EE a few days ago that should help you get it running right.
 
OP Again I stress "send us the gun, we will fix it" despite the fact that the barrel is a second hand purchase from someone else and that it was set up for the original buyer. As stated by others the 300 Blackout is not as simple to deal with as standard ar15s in 223.
Minor common problems may actually be successfully diagnosed over the interweb, but operational problems may not be as successfully solved that way. As simple as an AR is they can be a little tricky at times to make function reliably especially in the more exotic calibers.
 
I apologize I did not state the barrel type. This is an ATRS 223 1/8 Wylde Chamber Barrel purchased from EE. It was never used by the original owner. I put the parts together so I rather figure out the issue myself rather than shipping it. I do really appreciate the offer to help me out and for that I will make sure my next build the barell will still be from you guys. (Fit and finish is awesome.) Thank you.

My new buffer/buffer spring and extractor upgrade should be here any day. =)
 
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Suputin said:
I see in another thread a post by the OP talking about this carbine being a 300 BLK. It would have been helpful to this discussion if you'd noted that in the first place because a 10" 223 barrel with a pistol length gas system makes NO sense. However it makes perfect sense in a 300 BLK and it makes this discussion a bit more complicated.
Click to expand...

Not once I mentioned this rifle was a 300blk. =o/ But I do apologize for leaving some details out.
 
Are you sure the gas system is pistol length and not carbine length… if it is pistol length the gas block would be closer to the center of the barrel, if it is carbine length the gas block would be near the muzzle… A pistol length gas system on a .223 10.5” barrel would be pretty strange...
 
Mirk said:
Are you sure the gas system is pistol length and not carbine length… if it is pistol length the gas block would be closer to the center of the barrel, if it is carbine length the gas block would be near the muzzle… A pistol length gas system on a .223 10.5” barrel would be pretty strange...
Click to expand...

Yes sir. Used pistol length gas tube. Tube measured 6 3/4".
 
I hear of plenty of 10.5's with pistol length gas systems... weather or not they work is up for debate... however I have a pistol length, and its much less then 6", yours at 6 and 3/4" is getting close to carbine length,

read here for more on gast tubes http://www.m 4carbine.net/showthread.php?p=1414695

OP, what happens during the FTE's? is the round still in the chamber after, or partially extracted, but not ejected?

does the bolt cycle and slame a fresh round into the FTE one in, or partially in, the chamber?

if its the above, id say H buffer set up would be my guess as to the solution,
 
easysauce said:
I hear of plenty of 10.5's with pistol length gas systems... weather or not they work is up for debate... however I have a pistol length, and its much less then 6", yours at 6 and 3/4" is getting close to carbine length,

read here for more on gast tubes http://www.m 4carbine.net/showthread.php?p=1414695

OP, what happens during the FTE's? is the round still in the chamber after, or partially extracted, but not ejected?

does the bolt cycle and slame a fresh round into the FTE one in, or partially in, the chamber?

if its the above, id say H buffer set up would be my guess as to the solution,
Click to expand...

I had a carbine length gas tube and was too long. The round was hanging out from the ejection door. It gets pinched by the bolt while its loading another round and partially in the chamber. Will try again Saturday.
gas.jpg


Ended up using this
http://www .brownells.com/rifle-parts/gas-system-parts/gas-tubes/ar-15-m16-pistol-gas-tube-prod44641.aspx
 
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