In theory, it should yield a more consistent shot, as the inner barrel has two points of play in the outer barrel: at the muzzle, and at the hop up chamber. The theory, is that while it's difficult to stabilize play at the hop up chamber (especially since the OEM part is die cast - thus, loose tolerance), we can still at least tighten up at the muzzle. That's what the shim is for (or for rubber o-rings in some instances.)

At least this way, the muzzle position of the inner barrel will be much more consistent, rather than if the shim were not in place.

Damn you are making me disassembling my gun just to put the ring in.

More like you created the work for yourself by skipping the step. LOL. Don't blame the messenger!

Actually are we talking about the same metal ring? The one that I have is about the size as the rubber o-ring. Its diameter is bigger than the inner barrel, and it doesn't seem to fit anywhere. I also noticed that the inner barrel is already pretty flushed at the front of the out barrel (comp off).

Like I said, a picture is worth a thousand words. Help me out here.

Too lazy to take the gun apart, but the rings I have are identical to the following:

http://www.brotherprice.com/ebphoto/...20TONE%20a.jpg

I suppose the two rubber o-rings are backups to what secures the barrel sleeve. The metal ring (not so much a shim) is of a similar size but with a cut opening.

Hmm... interesting. I haven't seen that before. Does it fit on the recoil rod? I'm wondering if it acts as a dampening system. Best is to ask wherever you got it from.

So I have no idea why, but my FPS for my hicapa 5.1 has dropped by 100fps for some odd reason. I chronoed my gun a few months ago and it was at 285-290fps with 0.25g bbs.. I chronoed my gun yesterday and it was at 150-185fps with 0.25g bbs again.. I already cleaned the inner barrel, reinstalled the hop up rubber, and locktited my 2 hop up halves..I even tried using plumber's tape to seal the hop up rubber/inner barrel to prevent any gas leak. Ive got 4 mags and they all fire very weakly.. Any suggestions? Here is my part list:

TK twist barrel
SD POM air nozzle
stock floating valve
IK BBU

Is the piston head secure?

yup, its the piston that is fixed in the IK bbu.

What slide set up do you have?
I'm guessing something happened to your magazine route seal rubber? Room temp? Nozzle loose?

Have you tried without the plumber's tape?

I have a SD Limecat Phantera slide that I was always using. Room temperature is around 23-25C. In terms of the magazine route seal rubber, they appear to be okay. I even tried my friend's magazines with the stock rubbers and the FPS is still ridiculously low.

Brian, yes, I tried with and without the plumber's tape. Plumber's tape actually makes it worst for some odd reason.

I don't find it that odd.

What hop up rubber are you using?

Before i used the firefly hop up, but now im using the 9ball hop up. FPS remains the same if hop up if all the way on or off.