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View Full Version : New AR-15 build won't cycle!


localguy
09-14-2008, 9:59 PM
Hi guys. My new AR-15 build is wonderfully accurate with the standard iron sights, but it doesn't seem to cycle the rounds out after each shot. It is a mid-length gas-system using an A.R.M.S. folding front sight gas block. This is a custom upper built by David at riflegear. I was also shooting Fiocchi 55gr.

After the range trip I took the rifle home and stripped the upper, including disassembling the bolt, checking the gas key hole for blockages. There doesn't seem to be any problems in this case, but I have one interesting caveat;

It seems that there is some carbon fouling on my folding sight gas block. Has anyone encountered this before? Perhaps the gas block is not on properly?

Is it also possible that using a heavier, carbine buffer will prevent a mid-length gas system from cycling?

One Shot, One Dropped
09-14-2008, 10:01 PM
I would say that if you have a custom-built upper but are having problems with it, you should contact the gunsmith with questions.

I don't really know if the buffer spring would cause enough of a problem. It never has for me...

tankerman
09-14-2008, 10:04 PM
This is a custom upper built by David at riflegear.
Guess he forgot to test fire the custom upper.


It seems that there is some carbon fouling on my folding sight gas block. Has anyone encountered this before?
This sounds odd. Gas leak-by?

ChrisXD45T
09-14-2008, 10:07 PM
It might help some of the gurus here if you gave more detail about how and when the gun fails to cycle. Is it every round? Does it at least short-stroke, or fail to cycle the bolt entirely?

localguy
09-14-2008, 10:09 PM
It might help some of the gurus here if you gave more detail about how and when the gun fails to cycle. Is it every round? Does it at least short-stroke, or fail to cycle the bolt entirely?

The bolt doesn't even move. I had someone fire it after charging and the bolt didn't even budge one bit.

ChrisXD45T
09-14-2008, 10:12 PM
Every time? So essentially, it's a manual bolt action rifle right now.
Perhaps the gas block is not lined up with the hole in the barrel.

hybridatsun350
09-14-2008, 10:16 PM
It has to be the gas block alignment. If it was any other problem you would at least get bolt movement.

localguy
09-14-2008, 10:52 PM
It has to be the gas block alignment. If it was any other problem you would at least get bolt movement.

I guess I'm going to have to try to have it looked at. No confidence in myself as far as disassembling my upper beyond the bolt. :D

aplinker
09-15-2008, 12:38 AM
If it's not cycling at all you're not getting gas to the carrier, especially if you can cycle it manually.

That you see carbon on the gas block means you have a leak. At least you know you have a gas port drilled in the barrel. :D

You don't need a heavy buffer with a mid-length gas system. Those are for carbines that are overpressured. However, this isn't your primary issue.

Riflegear will fix it for you - David's a good guy. You're also in the same town as Randall, who can diagnose & fix it for you.

localguy
09-15-2008, 9:27 PM
I'm hoping the problem is as simple as the gas block misalignment and not something worse. :)

shark92651
09-15-2008, 9:42 PM
Bring it back in and I'll get it resolved for you. It's probably a mis-aligned front sight or perhaps something is wrong with the #41B, but I'll make it right either way.

localguy
09-18-2008, 9:10 PM
I do have a general question about this...does a Carbine spring and Heavy buffer prevent a Mid-Length gas system from cycling?

Pryde
09-18-2008, 9:14 PM
I do have a general question about this...does a Carbine spring and Heavy buffer prevent a Mid-Length gas system from cycling?

If it was the buffer, it would still partially cycle (short-stroke)

shark92651
09-19-2008, 8:59 AM
I solved the problem with this upper yesterday - the gas port was not properly aligned with the ARMS #41B. Cycling great now.