Help me make my under gassed AR run....

J

JDriver

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I re-barreled my SBR and it is now under gassed.
I am running a Mid-length 11.5" light weight profile from Faxon. Previously it was a carbine gas 11.5 medium contour. Faxon says the gas port is already enlarged to help compensate for there being almost no barrel after the block.
The gun runs perfectly when a can is on it, but will not cycle without. The can is a Gemtech Halo on BattleComp 2.0

I have an an adjustable gas block on it, that is all the way open.
FA BCG
Standard Carbine Spring
H2 Buffer

What parts would you recommend I change to help it cycle un-suppressed?
I have a standard buffer but that is the only spare part lying around.

Thanks
 
H2 is a heavy buffer, try using a lighter one or depending on how far back its going before it jams(not sure if you can tell) but maybe find a lighter spring? or cut a loop of the spring out and use the same buffer and see if that helps
 
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Zedhound;n52208 said:
cut the carrier? you sir are brave
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I don't think he was saying to cut the carrier but instead to buy one that has a semi auto cut instead of the full auto cut. Basically buying a lighter weight carrier.
 
Climberman said:
Zedhound;n52208 said:
cut the carrier? you sir are brave
Click to expand...

I don't think he was saying to cut the carrier but instead to buy one that has a semi auto cut instead of the full auto cut. Basically buying a lighter weight carrier.
Click to expand...
ok that makes much more sense
 
go 3/16th or .1875 on a mid 11.5 and let the gas block do the work.
 
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Always wondered about those 11.5" gunner barrels. Not much length for dwell. I guess they were designed for suppressors.

Seems like opening the port a c-hair is the solution.
 
NKD;n52256 said:
Always wondered about those 11.5" gunner barrels. Not much length for dwell. I guess they were designed for suppressors.

Seems like opening the port a c-hair is the solution.
Click to expand...

Its the only real option, I would not lightly open it up, I would go 3/16th or .1875 and adjust the gas block
 
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JBoyette;n52248 said:
go 3/16th or .1875 on a mid 11.5 and let the gas block do the work.
Click to expand...

I'd say this is they way.....pressure isn't the issue it is volume of gas.....also make sure your not loosing around the gas block and or the tube......I wonder if a tapered hole would work better to increase volume?
 
My first question would be...why did you change the barrel to begin with? Was the other barrel shot out? That type of barrel is made for shooting suppressed, though it seems like a solution searching for a problem.

As for the solution you're requesting, I agree with JBoyette. Open up the gas port and tune it with the AGB.

2nd option would be to try the H buffer or standard carbine buffer, though I would worry about the BCG outpacing the magazine spring and not stripping the next round from the mag at times if the springs and buffer weight weren't perfectly tuned. I'm not a fan of lightweight recoil systems on any gun I want to be reliable, which is anything I own.
 
I'm with BigWaylon ... sounds like you have a dedicated suppressor upper.

Don't get the middy SBR thing. Shorter than 14.5" it's like a dissipator... and we're all aware of what a pain those are to get to run.

If you're set on it, before modding the barrel permanently, I would try a standard carbine buffer and AR-15 BCG as some of the others have mentioned.
 
It ran like a top before, but I wanted to try something different. If it is a suppressed only gun, that is fine as well, but if I can make it run either way it would be great as I have a QD can on it. I can always put my direct thread on this and my QD can on a longer AR. Or, just build another upper.
So, no real reason besides of having plenty of ARs and liking to play with my Legos.

Thanks for for the comments so far, they confirmed what I was thinking but wasn't positive about.
 
This was probably mentioned but double check that the block is installed correctly and isn't choking the port at all.
 
I would switch the H2 out for a carbine buffer first. Then drill the barrel second if it still does not cycle.
 
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