G&G M14 Upgrades.

[Methos]

First off I'll say hello: "Hello!"

I am a frequent reader of these forums, but a rare poster as that handy search button normally provides all the answers I need, but this one truly has me stumped.

I got my first airsoft gun - a G&G M14 - about a year ago now and it has gone from stock to this:

EXTREME-FIRE SW MOSFET Computer.
Systema Magnum Motor (Short type)
Prometheus EG Hard gear set (Helical) & Reinforced piston (full tooth)
G&G M14 Upgrade Cylinder (type-0 / no ports) , Cylinder Head & Piston head kit for M14
Airsoft Surgeon stage 4 spring
Stock 6.04mm Barrel
Prometheus Hard (red) Hop sleeve
H-Hop bucking (black)

Now, that setup shot at 530FPS with .2's and could hit a man sized target at 200 yards - I also did all the upgrading myself. I finally decided to spend that last £50 and get an upgraded barrel, and after some research set for a madbull v.2 509mm (for M16 / AUG). The reason being that the G&G stock barrel is 517mm long and it uses an AUG hopup, same as an AUG (duh) and M16 variants.

The barrel arrived in the post today and I choro'd my gun before I put it in, the expected 530 came out on reader. I took it apart, put in the madbull 6.03 tightbore and chrono'd again.... 450FPS with a .2 ... eh?

So, I cleaned the barrel for factory impurities... still 450.
Did the "BB roll" test to see if the barrel was mis-shaped somehow - flawless performance.
So I took it apart again, this time down to the gearbox to check if I was losing compressing anywhere - but all seemed fine in there, even checked the airseal nossel but nothing seemed wrong.
Swapped out the Prometheus (hard) sleeve for a stock (softer) one - as the hard one has caused trouble previously.... 450
Swapped the hop unit (which is a nicely constructed metal one) for another one I had around. .... 450 still
Removed the hop bucking completely just in case it was protruding an abnormal amount into the barrel (though a quick eye inspection down the barrel usually identifies this I thought it couldn't hurt).... 450

Despite all of the above the FPS didn't change a bit

I was aware of the infamous "vacuum" problem that some people experience, but from some reading I have done around this site and others, it doesn't appear that it could be that either. Correct me if I'm wrong (and the answer is still relevant) but the "vacuum" only occurs when your cylinder can't compress enough air for your barrel? Seeing as this barrel is a) shorter and b) tighter than my stock one I can't see that being the case.

Any genius' feel like cracking this nut?

Feedback would be wickedly appreciated!

Methos.

[The Saint]

Shouldn't be a vacuum issue that that length.

Have you tried putting your G&G barrel back in to see if it goes back to your original 530fps? Just to be sure that nothing was damaged when you first swapped the MB barrel in.

[Methos]

Cheers for the quick reply.

I'm doing that as we speak, I just got fed up of fiddling with it so I wrote that post before resuming my "work" - I'll keep you updated.

[Methos]

Swapped them over, 530 FPS as expected...

[Donster]

is there an air-seal leak in the hop-up chamber area?

[Methos]

Well, potentially, though I can't say I know how to check for one... ideas?

[Donster]

wrap teflon tape around the connecting point of the inner barrel and hop-up chamber. If the FPS increases, you know what your problem is/was. If not, then take your gun apart and take the tape off and scratch-build from the beginning. i dunno, those are just my thoughts on this. i am not a gun doc.

[Methos]

Originally Posted by DONSTER 125

wrap teflon tape around the connecting point of the inner barrel and hop-up chamber. If the FPS increases, you know what your problem is/was. If not, then take your gun apart and take the tape off and scratch-build from the beginning. i dunno, those are just my thoughts on this. i am not a gun doc.

by the connecting point of the inner barrel and hop-up chamber, do you mean around my inner barrel where it gets covered by the hop sleeve, or around the hop sleeve where it's covered by the hop unit - or somewhere else? :P

The below shows the AUG Hop unit if you're not familiar with it:

http://www.airsoftparts.ca/store2/im...op-up-unit.jpg

Though it's not attached to the barrel, you get the idea.

[Methos]

I am one thoroughly confused airsoft player.

So, I normally run with the stock (soft) hop sleeve because the prometheus hard sleeve was way too tight on my stock inner barrel. Naturally when I changed over the barrels I put the stock sleeve on my new one, just on auto pilot I guess.

However, I'm so sure I swapped out the hop sleeves before posting this thread - it's like one of the first things to test with this sort of problem in my eyes. In any case, I just swapped the soft sleeve for the hard sleeve (which as I was putting it on was a much snugger fit) and viola, back to 530 FPS...

I'm such a tool. Sorry to bother you all, and thanks for the replys that were given!

Problem solved

[The Saint]

Glad everything worked out.

[Skladfin]

200 yards? your gun shoots out BBs out to 600 feet? No friggen way!

[Donster]

Originally Posted by Skladfin

200 yards? your gun shoots out BBs out to 600 feet? No friggen way!

i saw that too. i think he meant feet.... or at least that is what i made myself hope for

[LUTNIT]

Well some people have made claims of PTW's shooting out to 500 yards with red cylinders...

With a well tuned 400fps long barreled gun (at least 450mm inner barrel) I can usually easily get an effective range out to 125-150 feet and thats only 400fps guns (usually shooting .28's so they are only traveling ~330fps.) I have made kills out to 300 feet but that is lobbing BB's and having them land on top of people who are actually good enough to call it.