Fal gas system/tuning question

[Visceral_Malice]

So a few months back I got a hold of a fal for a ridiculously good price. I had some reservations because said fal was put together by a less than reputable company, but the price was right and I took the dive. I thoroughly inspected it and checked for all known issues that company seems to forget to check and everything looked great. The worst part was the sights were about 12" off zero, but nothing difficult to fix.

I have done some work on it and fixed it up to a really nice setup, but I'm having one issue that is distressing still. The gas system. I know how to tune it etc., but I'm running into the issue of it being wide open (on 7) and I'm still locking the bolt back just fine. I initially thought the springs needed to be changed, which they did, so I took care of that and its still the same thing. I know its no major issue, but its bothering me. I know most fal's run on the 3-5 setting. It shouldn't have enough power to lock the bolt if I have the system as open as it can get. I don't have it on the grenade setting either; I already checked that. Everything looks fine upon inspection, so I'm out of ideas. Anyone have any clue as to what the issue could be?

[panzermk2]

When you say "open" do you mean the port is at it's most open setting or closed all the way?

Also if this is a Century arms the little pin on the hold open that engages the magazine follower may be missing. Some FALs, mostly Sand Cut L1A1s had the pin removed to keep sand out of the action.

[Visceral_Malice]

Yes unfortunately it is Century. Seems to be a decent one at least. I mean I have the port at its most open and the bolt still locks back once the mag is empty. From what I understand it shouldn't have enough gas pressure at that setting to make the bolt engage the hold open. I've checked the port and I can see the piston, so its not blocked.

Its one of the newest CAI models and is composed of an Austrian parts kit. Overall it still functions fine, I'm just concerned something may not be assembled properly due to it being from Century. I don't know what exactly might be causing it to always cycle so much gas back to the bolt.

[panzermk2]

I run mine on 6 so your not that far off. Does this happen with all ammo or are you using some NATO stuff that is on the warm side?

I use the one round in the mag procedure to set my port. Load one round in the mag. Chamber it start with the port vent open 10 or 9. Fire if the bolt does not lock open on the mag close the vent one click. Repeat this until the bolt stays open. Just so you know your venting more gas out on 7. That means you rifle and bolt aren't slamming back as hard as they would at a 5 setting. That's better for your rifle less wear and tear. Also I don't know where you got that 3 to 5 number. My experience is 5 to7 on a L1A1 10 setting port.

[Visceral_Malice]

I solved the mystery. I found a post somewhere after hours of looking saying that a lot of cai's have ill-fitting pistons and over gas the bolt. Mine appears to have that issue. The piston does not float freely in the gas tube and binds up. I took off the piston spring and dropped it into the tube and it stops immediately and I can only push it by hang far enough to get the plug in. Now to order up a new piston and get this fixed.