Disappearing Air-Leak? - Help!!

2781 Views 7 Replies 4 Participants Last post by PsychoYumYum, Sep 14, 2015

PsychoYumYum

Discussion Starter · Sep 10, 2015

So.... this has been baffling me for a while. I have an CMYA M14, with upgraded motor, piston+piston head, and air nozzle. When I test compression its all pretty good (I know it could be better but I'll live with it). However here comes an the issue................ when I put the gun together I get about 190 fps if I load a single bb in the magwell or use a magazine BUT if I muzzle load the gun, tilt it back until I hear the BB make a seal, boom! 410 fps (which is what I was expecting)

So in summary:

(high cap) Magazine = 190fps (no hop set)
Muzzle Load = 410fps

I've tried this with different bucking, changing the hop, rhop even. its consistently bad

the best improvement has been trimming the lips off a bucking, I then get about 330 fps if I muzzle or mag feed the gun.

ideas anyone? I did try a google and haven't seen anyone else with this issue

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Reliku

· #2 · Sep 10, 2015

You could in theory purchase yourself a civil war outfit and muzzle load it on the field :hehe:

On a more serious note, it seems to me as if loading from the mag restricts the nozzle somehow. Can it move freely? It evidently gets forward when there's no mag inside, but it may behave badly when there's a bb in between the mag and the chamber... I'd look there.

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~Ranger~

· #3 · Sep 10, 2015

Definitely sounds like something is restrictions the bb on the back side of the bucking/hopup. If you say the hopup is all the way off, maybe there is an issue where the hopup isn't actually turning off. The adjustment screw may be turning, but its possible that it's not doing anything but turning. So, if the hopup is on too much, that can slow the bb down a ridiculous amount. Clear the chamber from any bb's. Then do a dry fire towards the floor.. THEN do a dry fire into your hand and see how much air pressure comes out of the barrel. Could be a ripped bucking, stopping the bb from moving thru freely. Could be a stuck hopup arm/actuator. Could be a nub, lodged sideways even. Wont really know till its taken apart and inspected.

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PsychoYumYum

Discussion Starter · #4 · Sep 10, 2015

Thanks for all the help so far!! I'm a believer in figuring out things myself.. and came to the same conclusion. I'm sure the hop is off as I've put the whole thing back together with no nub at all...just in case. the result is the same.

the only difference seems to be that if the bb touches the air nozzle, as it would if coming from the magwell then there's a massive air leak somewhere. if the BB doesn't touch air nozzle then everything is fine.

I've tried changing the air nozzle from metal, to plastic to stock... nothing has worked... i'm going to try again later. Thanks again!

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luke213

· #5 · Sep 10, 2015

Check the spring on the tappet may not have enough force to chamber the bb stopping before the nozzle fully seals to the bucking.

Sent from my XT912 using Tapatalk

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PsychoYumYum

Discussion Starter · #6 · Sep 10, 2015

Thanks for that! now that's something I haven't tried!!!!!!! the V7 Gearbox is odd but there must be something I can do

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luke213

· #7 · Sep 10, 2015

Yeah its a good system but frustrating to someone like me that's very used to version 2 stuff.

I'd just make sure that spring is strong enough because I can see that happening. Hop up unit double check that its sitting properly against the box too. I've had problems in the past with it sitting slightly out of sorts causing issues.

Sent from my XT912 using Tapatalk

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PsychoYumYum

Discussion Starter · #8 · Sep 14, 2015

Sooooo after a weekend of frustration, decided to change the batteries in my calipers... and the air nozzles turned out to be different sizes, 20.8, 21.2 and stock is 21.4. Put the non air seal stock nozzle on, m140 spring in combination with a 60 degree bucking + DIY silicon tubing Rhop, and hey presto! 392 fps with full hop or 450fps no hop. I have no idea if it fires straight yet... or if I need more hop (there's no nub in the hop atm). Thanks again for all your help!!!!

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