AGM M4 GBB

[raito]

+1 what sacairsoftsn00py said, I'm still using the stock hopup chamber & rubber, and I don't have the bb dribbling out anymore...with .2 bb mine can easily go over 70 m,

 

but the funny thing is that shooting on semi after that nice straight shot, the next one would drop after 40/50 meters, but the next one would fly up to 70 meters again, and then the next would drop again... problem with the gas cooling down?

[sacairsoftsn00py]

+1 what sacairsoftsn00py said, I'm still using the stock hopup chamber & rubber, and I don't have the bb dribbling out anymore...with .2 bb mine can easily go over 70 m,

 

but the funny thing is that shooting on semi after that nice straight shot, the next one would drop after 40/50 meters, but the next one would fly up to 70 meters again, and then the next would drop again... problem with the gas cooling down?

 

not likely.

 

which nozzle are you using? which magazine and gas are you using?

[Luis21]

Ok guys,

 

I just filmed a brief video comparing my newly arrived 5KU mags to my stock AGM heavyweight mag. Photobucket is being pretty ghey right now so I'll ave to upload and post the video tommorrow.

 

I'll most likely post it at around 8 pm PST or 11 pm EST for you east coast boys. Tune in tommorrow to see more about the 5KU mags.

 

I will also do a proper video review of the new steel JDT BCG as soon as it comes in.

 

Thanks,

 

-Luis

[Luis21]

Hey guys,

 

Sorry for the double post but I just realized that since it takes about an hour to upload, the video will have to air about an hour later.

 

So, it should be up tommorrow at about 9 pm PST/ 12 am EST.

 

Thanks,

 

-Luis

[raito]

not likely.

 

which nozzle are you using? which magazine and gas are you using?

 

I'm still using the stock bcg and nozzle, and I'm using bomber mags with green gas...

 

can't wait for your review Luis, I'm curious about the JDT bcg

 

-edit spelling

Edited September 15, 2009 by raito

[FearMeansControl]

I'm still using the stock bcg and nozzle, and I'm using bomber mags with green gas...

 

can't wait for your review Luis, I'm curious about the JDT bcg

 

-edit spelling

 

 

+1.. I've only got one of the 5KU mags, but I bought it the first week it came out... Has had a slight leak since day one in the valve that is minor enough that my laziness is stopping me from fixing it

 

Really curious about that BCG though....

[mutikasha]

Did some test shooting today. Setting was GP hop rubber, 5ku hop chamber, Element nozzle in AGM carrier, AGM nozzle 2nd gen in AGM carrier.

 

Element nozzle

Hop tuned to near lowest setting (dremeled the adjustment ring so it does virtually 360 degrees), .30 g bbs shoot perfect but with double feeds and spitting bbs. With hop set to 3/4 everything works fine, no double feeds, no spitting but with significant overhop and bbs sailing high. .43 g bbs go far and straight but I don't have enough of those. I have hit a gas can two out of three times at 50 meters distance ( ). Low gas consumption (did a whole two GHK mags withouth refiling). That butplug thingy in the upper receiver is missing, but I added some material to compensate for it. After adding the material the problem got worse, not one bb got right out of the barrel.

 

AGM nozzle

Cycles slower than an element one. I get a feeling it tends to get a bit stuck in the forward position and then needs more force to get out of the hop unit and cycle back into the carrier. No missfeds, double feeds or spitting bbs at any hop setting. With the AGM mag the bolt cycles pretty good but uses a lot more gas and cools down more quickly than with element nozzle. GHK mag has trouble cycling the bolt in auto mode (looses power rapidly), single is doable but with high fps variations.

.30 go good, .43's also

 

I would realy like to be able to use the element nozzle and .30 g bbs in my setup. Do you guys have any sugestions?

 

 

P.S. Sorry for the grammar, spell check died on me.

Edited September 16, 2009 by mutikasha

[raito]

I thought that butplug rubber thinggy was there just to prevent the charging handle smashing into the receiver, sort of a bumper... why would it have anything to do with how the nozzle works?

Edited September 16, 2009 by raito

[mutikasha]

One millimeter of difference in the nozzle position, may have a world of a difference, and may have nothing.

[snorkelman]

I thought that butplug rubber thinggy was there just to prevent the charging handle smashing into the receiver, sort of a bumper... why would it have anything to do with how the nozzle works?

 

because it governs the depth that the nozzle enters the hop chamber on the loading stroke

 

without the buffer the charging handle can sit further forward, when the charging handle sits further forwards the gas key on the bolt carrier can sit further forwards, and when the bolt carrier sits further forwards the nozzle sits further forwards. Voila

 

Is the element using negative or positive pressure? If its set for positive try to rig it for negative pressure and see how you get on

 

If BBs are getting knocked too far thru the hop then they wont be applying any standoff to the flute valve and gun will fire a blank (recoil only - which in itself is going to increase your number of cycles per fill). Then it'll cycle again strip a second BB and chamber that too, the first one already in there would then stop second one going just quite so far into the hop. So the positive pressure flute valve now gets depressed and gas finally makes its way out the barrel and down the spout firing both BBs.

 

Once you whack on a load of hop the first BB gets held in appropriate place and fires out the spout every time, no more doublers - trouble is you're applying so much hop to acheive that they're then overhopping - which has you reaching for cannonballs to compensate.

 

I'd make sure the hop rubber is surgically clean and dry as a bone (swab it with alchohol) was a classic symptom on escort guns slightest trace of lube on the hop and you were in that 'fire none fire two, fire one fire none fire two' scenario.

 

The AGM nozzle is negative pressure so it'll pretty much always try to fire a BB if theres one in the hop, even if the BB is so far into the hop that it would be too far to depress a positive pressure flute valve. Plus if theres differences in nozzle and loader length etc it could be the AGM isnt even pushing the BB as far into the hop in the first place..

 

If I was wanting a better idea of whats going on I'd get a 6mm cleaning rod with a flat face on the end (not a tapered or diagonal cut one) take the flash hider off the rifle and use the AGM carrier and bolt with hop set to minimum - then Id rack the bolt and let it slam home. Once Id done that I'd gently insert the cleaning rod untill I feel it just kissing the face of the BB and mark the end of it where it lines up with the muzzle with a fine marker

 

then Id rack the bolt back and while it was in that position I'd eyball the BB thats in the chamber to get a visual from that end as to where its sitting, then push the cleaning rod in far enough to knock the BB out the hop, and shake the BB out of the receiver. I'd then repeat again a good few times over to see if the mark stays in a more or less consistent place.

 

then Id do the same with the element assembly and compare - is the BB going further into the hop so that the cleaning rod doesnt fit quite as far down the bore before making contact, when I rack the bolt and look at the chamber is the BB visibly further forward etc?

 

its a pretty crude method and if the variances are small isnt going to do much good, but it should make any large discrepancies of a couple of mm or so in 'depth of feed' apparent

Edited September 16, 2009 by snorkelman

[raito]

ah thanks for the explanation snorkelman... maybe I should glue that rubber pad just to be safe, mine came loose a couple of time

[mutikasha]

Is the element using negative or positive pressure? If its set for positive try to rig it for negative pressure and see how you get on

 

If BBs are getting knocked too far thru the hop then they wont be applying any standoff to the flute valve and gun will fire a blank (recoil only - which in itself is going to increase your number of cycles per fill). Then it'll cycle again strip a second BB and chamber that too, the first one already in there would then stop second one going just quite so far into the hop. So the positive pressure flute valve now gets depressed and gas finally makes its way out the barrel and down the spout firing both BBs.

 

Once you whack on a load of hop the first BB gets held in appropriate place and fires out the spout every time, no more doublers - trouble is you're applying so much hop to acheive that they're then overhopping - which has you reaching for cannonballs to compensate.

 

I get now what might be happening here. In that element nozzle I can see that the flout valve is just a tad out of the nozzle. When the bb is in the hop unit, should it be slightly depressing the flout valve to allow the initial gas flow behind the bb?

Can I somehow alter the nozzle to use negative instead of positive pressure? Maybe using parts from the old AGM nozzle?

Thank you for the explanation for the NPAS versus PPS system. Is there a schematic of one versus another somewhere. Used google but with no results.

[snorkelman]

On the AGM nozzle assembly the flute valve is held open with the spring (spring goes at front around long part of the flute valve)

 

On a positive pressure system the spring is behind the flute valve pushing it closed (relying on the BB being in the right position in the hop so that it can push on the tip of the flute valve to force it open)

 

 

 

 

 

[mutikasha]

Thnx for the info... just realized that going from page 1 of this review to page 67.

Edited September 17, 2009 by mutikasha

[mutikasha]

Adjusted the nozzles, they work like a charm now. Thnx for the info.

Anyway, the QC on those element ones isn't to great. I don't mean on the nozzle itself but supplied pins don't fit the holes so you have to make new ones. Also one of three side lock plates doesn't work to well. When assembled for negative pressure they give 390-405 fps constantly trough 7 shots in one second intervals.

[snorkelman]

good to hear it helped ... granted they really should be abe to work in positive config but way I see it if negative gets round the problem then why make life harder than it needs to be

 

Million dollar question is wether the elements work better in negative config than the AGM ones do (ROF gas consumption etc) though my guess is you probably wont have had a chance to do a fresh compare as yet?

 

[mutikasha]

good to hear it helped ... granted they really should be abe to work in positive config but way I see it if negative gets round the problem then why make life harder than it needs to be

 

Million dollar question is wether the elements work better in negative config than the AGM ones do (ROF gas consumption etc) though my guess is you probably wont have had a chance to do a fresh compare as yet?

 

Your guess is right , no time now for an extensive test.

I wasn't satisfied with the replacement AGM nozzle with the ROF and gas consumption when I was on my last game. It would cool down the mag rapidly (in like six shots). Indor fps testing and dry firing on auto proved much more reliable, and consistent with the element nozzle.

Anyway, going to a two day fight. I will carry two element nozzles and one AGM nozzle in three separate bolt carriers. I think it will be enough

[snorkelman]

hehe aye, if not you can always throw them at people to keep their heads down

 

[mutikasha]

Back from the skirmish. No nozzle brakes, no malfunctions . Total rounds spent, around 500 bbs. Not much though. Beore that I did another 600 rounds in the testing phase so it is still ok after 1200 rounds with the element nozzle. AGM nozzle has slighter more power then the element one (around 430 fps while element one sits in the respectable 400's using a standard barrel).

Problems observed:

- extreme coll down. Anything surpass a 5-6 round burst is not good. Power drop is significant in 20 C temperature.

- with every shot, a cloud of gas exited (noticable one) the barrel behind the bb. My nozzle is temporarily set to negative pressure so it is probbably set to spew to much gas behind the bb before the bolt starts to cycel. Maybe adding some shims on the float valve would be helpful in achieving higher gas efficiency and thous less cool down of the mag.

 

I'm currently using Abbey predator ultra - many of fellow airsofters have complaints about this gas - low power, to much lube, high cool down -maybe this is the starting point of my problems.

What gas are you GBBR users using in your guns (other than pure propane and duster)?

In what temperatures does your gun operate successfully?

[snorkelman]

re the cooldown

 

does it do same in semi and in auto? e.g does 5 or 6 shots as fast as you can cycle the trigger in semi produce a similar result to 5 or 6 shots in auto

 

if not then check the hammer lock functionality, hammer following the bolt carrier home in auto (rather than staying put till the carrier gets all the way back into battery) will start gas release before the nozzle assembly is lined up over the port in the mag and thats going to waste gas

 

 

reshimming the flute valve will end up in similar situation to a NPAS - you'll bring the flute valve closer to its closed position and reduce flow to the barrel so while you'll save gas you'll also reduce FPS

 

Not tried it but I'm wondering if a weaker flute valve spring might be a better option as gas might shut off faster on BB exit, but without altering the rate of flow being supplied while BB is still in the barrel - that might cut down the cloud of gas you're getting after BB exit without having same impact on FPS as shimming it closer does

 

really depends on how much of that noticeable cloud is down to excess gas still being sent down barrel after BB exit.

Edited September 20, 2009 by snorkelman

[mutikasha]

While shooting, didn't observe any gas escaping trough the side so I think the hammer timing is ok. I will check it though, just to be sure.

I realize that adding shims would direct less gas into the barrel and more to the blow back but (theoretical discussion follows...) fps shouldn't drop noticeably because there is more than enough gas pushing it out. The amount of gas diverted to blow back shouldn't be much larger because the blow back cycle would start sooner and released the valve lock on the magazine thous stoping the gas flow in the magazine.

Also, I love your idea of cutting some material from the float valve spring letting it to close more early.

Next thing on the to do list (unfortunately, this will have to wait a while...no time just now) - as I have three element nozzles I will test them in three different setups - positive pressure systems (will test every nozzle using cannonballs and 3/4 hop setting, as pps setup only works like this), negative presure system with normal spring, and negative pressure system with trimmed floute valve spring.

 

I would really like that somebody give me some info on which gas to use. What about winter gas?

 

EDIT: @ snorkelman I just realized that you also said that the gas amount used will be less if I used shims.

Edited September 21, 2009 by mutikasha

[colazel]

How to shim the flute valve ? any pic or diagram?

 

thank

[mutikasha]

Somebody already described how to do it in this thread it. Came across it several days ago. Don't know on which page was it but try starting from page 40.

[HOPPERSAN]

Question about the new jdt bolt and nozzle that came out on ebairsoft . They have listed :Play attention the bolt can only match Inokatsu type Nozzle

 

How does that apply to the agm users ? do inokatsu use different hop up or anything?

 

Are they saying that if the metal nozzle were to break only the Inokatsu nozzle will work for a replacement or that you can only use that specific bolt carrier or bolt carriers made for inokatsu e.g. no airsoft surgeon vltor stuff? Anyone know ..Thanks

 

.....Luis21 eagerly awaiting your review thanks

 

[Luis21]

Question about the new jdt bolt and nozzle that came out on ebairsoft . They have listed :Play attention the bolt can only match Inokatsu type Nozzle

 

How does that apply to the agm users ? do inokatsu use different hop up or anything?

 

Are they saying that if the metal nozzle were to break only the Inokatsu nozzle will work for a replacement or that you can only use that specific bolt carrier or bolt carriers made for inokatsu e.g. no airsoft surgeon vltor stuff? Anyone know ..Thanks

 

.....Luis21 eagerly awaiting your review thanks

 

Yes, I noticed that. Funny thing is that they listed it like a week after they listed it.

 

One thing though, after looking at the photos, the JDT carrier looks just like the Inokatsu. Lengthwise. So that means that it probably won't cycle in an AGM/WA receiver.....

 

This is NOT confirmed.

 

I will be able to verify it by midweek. Let's hope that it does fit and work. PX-Airsoft has the JDT carrier listed as WA/AGM/JG compatible...

 

-Luis