G&P M4 upgrade to fps 420
 

Hi there,
I am considering upgrade of my AEG GP-625 to fps 420-430.

I choose these parts:
PDI 210% spring
Phoenix Super Power Gear Set for Marui AEG
Guarder Infinite Torque-Up Short Type Motor
Prometheus 6.03mm inner barrel (285mm)

My question are:

Is this spring suitable for V2 gearbox?? I bought Guarder M130 (they say fo any AEG) spring but I could not fit it in by any chance, it was too long...

Is this barrel suitable for my gun, even though is designated for TM MC51, but length is ok... Design should be all the same right??

Is these gear set suitable, quality and durable for these configuration?? I have titanium teeth piston (made in Czech republic by PowerUpgrade) which is excelent btw, but my last tooth at sector gear is totally rub off.

In combination with mentioned motor I would like to get ROF about 15-20 but not to high...
I didnt find ratio fot hese gear set but hopefully could be about 21...

Is this a good motor?? I dont want to spend too much money for systema motors....

My current configuration:
M4 made by G&P upgraded by WGC
Systema piston silent head
Standard Systema teflon cylinder (no bore up)
PDi 170% spring
PowerUpgrade all titanium teeth piston
6mm steel bearings
Systema standard ratio gear set
Systema hop-up
GP M120 motor
9,6V Sanyo 3300 mAh

Thanks for any advice....

Hot gun hot gun....

1st of all why 400+ fps it's not going to make you win more, you'd be stuck playing outdoors.
2nd I'm pretty sure you don't know your ROE for a hotgun
3rd It's going to be expensive to upgrade and maintain a 400+fps gun
4th Get Age verified no way I am trusting someone who hasn't got their AS License ( Age verification)

Hope it helps

1st - I dont want to win more, but shoot long-range.
2nd - what is ROE? ROF = rate of fire (130 BB - one magazine, on full auto gone in 8 seconds = 16 BB/s)
3rd I am aware of it, 420 is not that much I think
4th Can't. And yes, I dont have AS license, why should I. I am not from america but europe, 18+ is only limit in Czech Republic. I am 27, btw.

I am just asking how to upgrade my airsoft gun, no how to make a bomb! Jees....
If you dont want to help or you can't keep your comment for yourself, thank you.

Don't know about the gearset...any quality torque up set should work fine.

Guarder Infinite Torque Up motor will work...M4 rifles require a LONG type...not short type motor.

An inner barrel..is an inner barrel...the hopup rubber cuts are all the same (note: M14 and some sniper rifle inner barrels are different).

The MC51 is fine. Is your cylinder ported...it should be.

Might just be a language thing....but metal bushings will last longer than bearings

an M120 spring might give you something close to 420...it'll be easier on your mechbox and the extra 10fps won't matter at all.

Use heavier bbs.

Ill check the motor again, just to be sure... GP M160 could be good as well I think.
What is ported cylinder??
Yes, I have metal bushnigs - language thing.
I am using 0,28 BBs

ROE is rules of engagement. Meaning the hotter your gun, the more disipline required in close combat engagements. More of an etiquite thing than a technical thing and very little to do with your question.

Choice of battery will be important here as well.

Thanks for explanation...
I have a battery 9,6 V 3300 mAh

But as I explained above, mofset will solve the problem with too high fps and rof

Many people assume that if they throw enough money into upgrades, the guns will run perfectly forever...this is simply not true. These guns, from the factory, were never designed to be upgraded. As soon as you start upgrading, you reduce the lifecycle of every single part in the mechbox. I've been tinkering with these thing for the better part of a decade, and let me assure you, there is no gun that will run forever (although I have a totally stock TM AK47 that has seen in excess of 200,000 rounds).

So, here's my advice to you.

PDI springs are very inconsistent. I'd go with a Modify or Prometheus spring, personally.

The G&P M120 is a good motor, but not necessarily for your application. G&P rates its motor by spring power, so it's designed for an M120 spring....you're looking more at M130/M140 range with your choice of FPS. Personally, I would use a G&P M140 Torque motor, or even an M160 Supercharger. I have found the quality of Guarder motors is hit-and-miss, but I have all 3 types of G&P motors (120, 140, 160) and all have been great.

The cylinder - you will want to replace the M4 cylinder with a MC51 cylinder. Matching your cylinder's internal volume to the barrel length/volume is critical.

Using 6mm bearings in a high-fps gearbox is a recipe for disaster. Either buy an 8mm bearing gearbox and use high quality ceramic bearing (like Kanzen) or just use plain steel bushings...or, go with Modify Modular gears.

Your gear choice is fine for this setup, although I am not a big fan of Pheonix's "self shimming" setup - what happens when a spring wears out (and all springs WILL wear out)? I'd suggest looking at the Modify modular gearsets - roughly the same price as Systema, and just as good, but you won't have to mess around shimming them. You can get a High Torque set of these gears with a ratio of 21.6:1. I use these in almost all my guns now. Prometheus also make excellent gears. I'd also pick up a stock Tokyo Marui v2 gearbox shell (they can be had for about $40).

Since version 2 mechboxes all have the same design flaw (the front end inevitably breaks in cold weather and with a high-fps spring), you will also have problems with this. Since you are using a G&P metal body already, it would be worth picking up an Ajax Customs Shock Transfer System. A small price for a good investment.

http://www.tacticalairsoftsupply.com...ade-parts.html
YouTube - Ajax Custom Shock Transfer System Test G&G M16 564 fps Airsoft Rifle

I personally would not use a all-metal tooth piston. In non-stock setups, the piston is generally the part you want to wear out first....it's cheaper to replace a $20 stock TM piston than a $100 set of gears, as you now know.

You mention having a Systema hopup, but not which hopup rubber you use. I prefer Prometheus Hard, or, (assuming you can find it) a Firefly "Kurage/Spicy" hopup rubber.

Alot of good advice was mentioned by Skruface and M1024,

I would go with the prometheus/modify spring, and if you are trying to get more accuracy at a longer range just swap the spring to prom 120/135, and put in a longer barrel.

A prometheus Neo hopup set w/ rubber (firefly, prometheus either one) and 407mm+ barrel will probably make you and your wallet far more happier than what you have originally planned.

FPS has very little to do with range, you can get the same range and accuracy at 400fps and 310fps, it all has to do with the quality of your internals.
The piston is overkill, you could get away with using a systema piston with 3 metal teeth on it. 6mm bearing tend to explode, anyway I'm pretty sure you have 7mm bearings since it's a G&P. And you can use regular torque gears at 400fps as long as you have a 9.6v mini or an 8.4v large battery

Thanks for your advice, I really appreciate it...

My first upgrade has been made by WGC shop so i was not exactly sure about my internals, so I made a deep search and found this:
(my current internals)

Guarder (accoring to WGC upgrade plan) or G&P metal Hop/up unit (according to visual comparation - no guarder sign on it), not sure about rubber, probably original GP
7 mm steel bushings/bearings - probably original GP

Systema teflon cylinder set I think cylinder size is suitable for 285 mm long barrel (not planning to get longer)

Systema gears

Guarder Air nozzle - bore up (larger hole diameter than standard)

Guarder enhanced tappet plate
Steel spring guide

Now back to your answers...

About PDI spring, I heard only the best, so I am little bit suprised with your advice... So which Prometheus spring is equivalent PDI 210 or rather fps 420 with these internals? How about the length? I bought guarder m130 and there were no way how could I put it in...too long. PDI is about 16 cm long.

GP M140 motor was also my first choice then I read somewhere that is not powerfull enough comparing to m120, so i will probably go with m160, i am just little bit afraid of too high rof, hopefully gears with 21,6 ratio will slow it down...

Cylinder - as I said, I see no reason to change it.... Enough volume for 285 mm long barrel

About bearings/bushings - it is steel, it is 7mm, but not sure if bushings or bearings, probably original GP - How can i see the diference? Is it enough for M130 spring?

Would you recommend to change hop up rubber??

I found Phoenix new Shock absorbable design gears quite interesting, but does it really works or is it just theory??? Price is also not really small... $96
I can use standard shimming insted of small springs anyway..

Ajax Customs Shock Transfer System is very interesting piece of HW, but for that price I can have brand new gearbox.... And i am not planing to get to 560 fps in freezing weather...

That piston cost me $50 usd, i am not planing to replace it. I already broke brand new systema piston just after few shots... This one is still good as new...

I can't help but notice:

MOSFET does NOT lower your fps. The spring's release is the contributing factor, all the MOSFET does is control how fast it is compressed... Physics does the rest. If you make your gun shoot 420fps, it will always fire 420 fps, the MOSFET will only allow you to shoot 420fps at different rates of fire.

Of course, you are right...

Dude, he's not from Canada.

Mosfet does not make up for too small of battery, but your battery should more than do the job. I thought that you were on crack when you said mosfet would control rof until I clicked the link. That is an interesting motor controller. Thanks alot, now I have something else I want to buy.

The problem with the spring being too long is probably because you have bearings on both the piston head and the spring guide. Sometimes a longer spring will fully compress and jam without the piston being all the way back. This can lead to the piston stripping or breaking. In all honesty, you only need bearings at one end. Usually, that should be the spring guide end...less weight in the piston head is a good thing.

As for comparable springs, our own Illusion made this excellent spring chart a few years ago:
http://www.airsoftcanada.com/SpringChart.php

I'd go with a Prometheus MS120 for your application.

If you're using a good programmable mosfet, you can slow down your ROF with that.

The problems with mechboxes cracking, *ESPECIALLY* v2 mechboxes, tend to start when the cylinder is not matched to the barrel. When it holds too much air (such as an m4 cylinder, with an internal volume meant for a 363mm barrel, is used with a 285mm barrel). The bb will actually exit the barrel before the piston is fully forward...with no backpressure to slow it down, the piston slams HARD into the cylinder head, just as if you were dry firing. This is not good. I urge you to consider getting a cylinder that's matched to your barrel, otherwise be prepared to buy plenty of mechbox shells.

If it's a bushing, it's a single solid piece of steel. It will look like this: http://redwolfairsoft.com/redwolf/ai...l?prodID=21829

Bearing bushings are usually a mutli-piece design. They have a metal bushing, some small metal ball bearings, and a metal race to keep the bearings inside the bushing. They look like this: http://redwolfairsoft.com/redwolf/ai...l?prodID=17813

The problem with bearings is their ability to handle the load of a high-powered spring. 6mm bearings and cheap 7mm bearings will fail under load, the race will break, and the ball bearings will end up shooting into you piston and gear teeth, increasing the chances are they will be ruined as well. If your bearing bushing fails, you may have to replace the piston and gears along with the bearing bushings themselves. The larger the bearing, the more stress they can handle....8mm can handle load better than 7mm, which is in turn better than 6mm. However, "bargain" bearing manufacturer will often use an oversized bushing bearing case and still use the same ball bearings as they use in 6mm bearings to make them cheap...so buy high quality bearing bushings if that is the route you want to go. Generally, bearings with ceramic ball bearings are better than those with steel, as ceramic is both smoother and stronger. Kanzen makes the best ceramic bearing buchings you can get for an airsoft gun....they run about $35 a set.

In this case, I would try to match the hopup rubber with the velocity you intend to shoot. A new (harder) rubber designed for higher FPS will give you more shot-to-shot consistency.

There's an old thread on these gears here:
http://www.airsoftcanada.com/showthr...=phoenix+gears

You could PM Illusion (or perhaps he'll comment) and ask him how the gears worked out for him; I've got no personal experience with them.

Realize that the v2 mechbox has physical limitations based on it's design. It's not about "if" it will break...it's about "when". If you are using a version 2 mechbox at more than 280 fps, it will break. This probability is increased the higher the FPS. It is compounded when you do not match the cylinder and inner barrel, as stated above. After you have replaced 2 or 3 mechboxes, you may be wishing you spent that $45 after all.

A Systema red piston or a Systema black one? The red ones have had problems for as long as I have been playing....keep in mind that pistons are designed to be the replaceable part in your mechbox....it's the cheapest thing to fix, and when a plastic/nylon/POM piston fails and chunk go flying into your gear teeth, they're much less likely to do any damage to the gears. A good nylon piston with properly adjusted angle of engagement will work as good (if not better) than an all-steel (or titanium)-toothed piston at a fraction of the cost. But hey, it's your money.

According to chart Prometheus MS120 is the same strangth as my PDI 170%. Where is the improvement?
If I remove bearings on piston side, I'll get extra 4 mm, but spring is still 175mm long. It would take a lot of struggle to fit it in. Is there any special way to do it? Not mentioning the possible jamming.


Which cylinder would you recommend then?
Or maybe I can just drill a larger hole to the cylinder to lover total volume. No need to spend anotehr money...
The cylinder I have is recommended for 200-400 mm barrel, not sure if 100 mm will lmake any difference...

Hm so I have ball bearings after all. I will buy new ceramic bushings then. (do they have any at redwolf?) Is 7mm enought?? Otherwise I would have to buy new gearbox with 8 mm holes or drill new holes to my current one to fit 8mm bushings.

New one added to the basket...

Ok, ok I will consider... Would you recommend any shop? I have found just one...

Black one, funny thing is I have shot about 100 bb with this brand new gun when the last nylon tooth broke off.

I was under the impression you wanted to achieve 420-430 fps. The MS120 will get you there. If you want more fps, buy a slightly stronger spring.

I'm not sure I'm getting what the problem is? Not all springs are the same length, diameter, or made of the same wire. Every manufacturer's tolerances are different. If you're trying to find a spring the exact same length as your PDI, good luck. I've never had issues with Prometheus parts not fitting.

I'd go with this, but that's just my opinion.
http://redwolfairsoft.com/redwolf/ai...l?prodID=17683


Unless you have some pretty high end machinery, I wouldn't try to enlarge the bushing holes yourself....get even one of them off-centre and you'll be buying a new mechbox, bushings, piston, and probably gears.

Personally, I would just buy a 8mm gearbox and Kanzen 8mm ceramic bearings, but since you're on a budget, get Kanzen 7mm ceramic bearings and you should be ok.

review: http://infectedairsoft.wordpress.com...ball-bearings/
buy here: http://www.airsplat.com/Items/AC-UPI-KZ-SYN-7.htm

I would say.... G&P M140 motor (your M120 motor may just work perfectly fine), use that prommy barrel, get a prommy hard hop-up rubber, and their MS120 spring, that AJAX STS is a pretty good idea too, your gearset set should be okay to use, and if you have the G&P white piston that should be okay as well. You'll definitely need to swap those bearings out for solid bushings though, and get a matching cylinder for your barrel length. Modify electroplated ones are nice.
By the way, you can keep the bearings on your bevel gear, but installing 6mm solid bushings on your spur and sector gear is still highly recommended; bearings are meant to take high speed but not high impact applications.

What is your choice??

Prometheus Double Torque Gear Set + Kanzen 7mm ceramic bearings
total $125
OR
Modify Modular Torque Up Gear Set for 7mm Gearbox (in case it will fit G&P 7mm gearbox)
I also found "Smooth" version here Which one do you think is better?
Older version seem to be more durable cause have two rails....
total $80

Consider quality, durability and M130 spring...

Since M160 is for the same price as M140, why should I go with M140??

Both companies (Prommy & Modify) make very high quality parts (Modify was an OEM manufacturer of Guarder internal parts for a looooong time). I'd have to assume that Kanzen's ceramic bearings are better quality than Modify's steel ones, though.

Assuming you know how to shim gear well, the Prommy/Kanzen package is better overall, although I think the Modify "smooth" gears are a better buy considering the price. I *really* like the Modify Modular gears, to the point that I specifically buy gearbox shells that will accommodate them (see below). I have 5 sets of the older ones (not "smooth") in guns from 280 fps (high speed) to 470 fps ("high torque") that I have been using for 3 years and have never had a problem.

Be aware that Modify modular gears (the old ones with 2 rails on the frame) will not fit in some aftermarket "reinforced" mechboxes, as they were designed for a stock Tokyo Marui mechbox ONLY. The G&P reinforced gearbox will not accept them. See my post here for more info:

New Modular Gear Set by MODIFY - Page 3 - Filipino Airsoft (FAS)

You will need to get the "smooth" set for your reinforced G&P mechbox if you want to go with Modify gears.

About the M140 vs M160 - the M160 is G&P's answer to the Systema Magnum - it is both high speed and high torque. Since you wanted to keep the ROF down, the M140 (high torque only) is a better choice. However, if you have a programmable MOSFET that allows you to adjust motor speed, the M160 would be a better value.

Just for curiosity....
I have this systema teflon cylinder
You recommend cylinder mentioned above...

I have compared both, the length from one end to the beginning of the hole and systema has shorter length for about 1%, in case that the diameter is the same, then volume for both cylinder are the same as well...

Of course I was calculating it just by picture, so maybe somebody can have different opinion...

you need the modular smooth set.
Prommy should have stronger gears, but IMO 420fps isn't enough to warrant a double torque gear set. They'll end up being the same price anyways; a smooth modular set+gear key should be something like 110 USD.

but I dont need a key, do I?????

it depends on where you order from. Some kits will include a mini key, some will require you to buy a seperate one. But you'll need to adjust it to fit a G&P mechbox

maybe I can ask seller to do it....

Some people dont recommend me a prometheus barrel. Some say it lowera their fps, or it didint fit at all becouse its bigger thickness....
Does any body have simmilar experience? I also have been recommended to try KM barrel. Are they good?

Does Prometheus EG Barrel 363mm for M4A1, SR16, SG551 fit into G&P Silencer or this one?
Does anybody have this combination?
GP Stubby has 109 mm length.
GP NSW Silencer has 190 mm length.

Wow. Never EVER heard of anyone complaining about a Prommy barrel. KN is good too, as are the original Systema 6.04 tightbores, but IMHO, Prommy is the best. Although, dollar for dollar, I personally think that Madbull Python v2 barrels are a great deal. I used them in a couple of my guns.

I've also never heard of someone who couldn't fit an inner barrel through the outer barrel, or a silencer. If the hole in the tip of the silencer is too small, use a drill to open it up. If the inner barrel doesn't fit past the end of the outer barrel (I once had this problem installing an extra-long inner barrel into a TM AK47) check to see if there's any metal flash left over from the casting process around the hole around the flash hider. I had a tiny ridge I had to file out of my TM AK's flash hider so a Systema inner barrel would fit through.

I have no experience with either of those supressors.

I heard that Guarder bore up air nozzle is shorter for about 1 mm. Could this be reason of my low fps.
Is Deep Fire Enlarged Air Nozzle (for M4) better?
I made a can shoot test to determine my fps, and it didint penetrate bottom, not even both sides (just one) of the can. ( 0,2g BB) So it is probably less then 350 fsp...

Precision barrel:
Madbull 6.03 $35 or
Deep Fire 6.04 $35 or
Prometheus 6.03 $48
??? (your choice)

I can't comment on Deepfire parts. I don't use them, because many other AEG builders I talk to say they are garbage, and I don't like to waste money, so I don't put garbage in my guns.

"Enlarged" nozzle sounds like some sort of Engrish description of a Bore Up nozzle.

And please, get access to a real chronograph. The can test is crap; it's very inaccurate because the thickness of metal used in soda cans varies from place to place.

if a prommy barrel is only $13 more, there is no reason not to get one.

Thank you guys for all your useful advices...

battery trouble
 

Hello again,
there is one thing I am struggling with. My Sanyo 9,6V 3300mAh battery.
After I full charge it and leave it be over night, it discharge itself, so the motor wont spin even though it tries (you can hear click sound). It seems to be quite strange. After I plug it in the charger for few minutes, than it is able to spin the motor. My charger is TLP Fuzzy Logic Expro
Also when I am charging the empty battery charger stop itself for about 30 minutes indicating that battery is charged, after I plug it again it continues with charging for another 30-60 minutes. I have to do that approx 4 times until the charging period shortens to less than 1 minute…
I don’t know where the problem is , battery and charger is 1 year old and very rarely used.

Update:
I was reading through the forum and found one topic where has been said to charge new batery with 0,1C, If I understand correctly it means to charge new battery with 3,1V (in case of 3300mAh). I never did this. I always charge with 1,2 V.
Maybe I could try to deep cycle it with 3,1 V. Hopefuly it will wake up...

Your problem is certainly battery if it's 1 year old and not properly cared for it is likely dead or close to it especially if is rarely used. NICD packs should be cycled once a month or two. and NiMH packs topped off.

What is the chemistry of the pack?

Charging at .1c-0.5c is the best way to take care of your pack in the long run.

Its NiMh

Do not cycle Charge NiMH it will kill your battery, You should be just topping off the battery every couple months or before you play.

And normal charging voltage 0,1-0,5C??
And first (after purchase) charging voltage 0,1C?? (formating)

I tryed to charge my current byttery with 3V, but I could set on my charger only 2,3 V max. So i discharge it and then it was possible to set charging voltage 3,0V (and more).
But during charging, voltage slowly dropped from 3,0 to 0,8V.
Mybe it was some protection function from charger to keep the temperature of baterry down, or I dont know. Battery was warm, but not hot.

I'll buy a new Elite4000SC battery anyway...

thats what I was doing for whole time....

After partial upgrade
 

So after almost final upgrade my gun status is:
chrono: 300-350 fps (0,2g bbs)

PDI 170% seems to be very incosistent and weak spring
I would expect higher (aprox. 400) fps with this spring...

* inner barrel Prometheus 6,03 - 363 mm length
* standard ratio systema gears
* systema hop-up
* GP M120 motor
* new elite 4000 mAh NiMh battery (quite high ROF)

Ater installing new barrel bbs are shooting quite inaccurate. Aprox 20-30m and then its going up and down. I tried to remove any oil from the rubber (washing in hot water) but no difference.
I am going to be despered, still no satisfied wiht my very expensive gun....

You used a PDI AEG spring.. That's your problem.

Go get a prometheus M120 if you want 420ish FPS.

Is this your model?
http://www.gp-web.com/en/productspop.php?pid=1535

PDI210% is approximately around M130 spring rate. Provided if your smithing skills are good enough and you’re running both ends with bearing, you’ll get that figure.

I’ve not handled an original PDI210%, accidentally bought a fake one :’( , but generally PDI springs are longer than the Guarder’s.

The spec says it’s 8mm Bearing GB. Just change it to a 8mm bushing. Bearings are a no go for high springrate nor a super high ROF setup.

Get a good brand 11.1v 15c or 20c lipo. Then get the JG M-93 Red Motor. Pair it with stock ratio gearset (reinforced, but stock ratio). Should hit the ROF you’re aiming. Get your AOE, shave the 2nd and 3rd tooth flat to avoid pre-cranking/stripped piston.

Are you sure your AEG uses short stem motors? V2 gearboxes usually uses long type motors (unless if it’s VFC/Dboy’s PDW, which uses mid length motors). Those programmable MOSFET systems can in a way, control the ROF by playing with motor speeds. Unfortunately, FPS is fixed with your hardware.

Questions:
Is the “PowerUpgrade all titanium teeth piston” full metal or was it polycarb with metal tooth? Full metal (heavy) pistons aren’t good for high ROF setups.

have your system properly cronoed for both FPS and RPS. That will get you actual figures instead of guestimation. Parts is just half of the equation. Skills plays an important role at the final results too.

I've seen 3XXfps with a M140 spring too. I've also seen 480+ fps with a stock AnK spring. Best thing is, the 3XXfps with M140 spring sounds much more powerful than the 480fps stock spring. LOL

What is the most suitable piston for my gun? My piston with all metal tooth is lowly getting KO. So I am considering to buy a new one.
I am using spring Prometheus MS135, modify smooth gear set torque and Systema silent cylinder and piston head.
Can I use sorbo pad together with systema silent piston head? (replacing the rubber)
THX

Thanks for your answers G26.
yes

I already have a new spring - Prometheus MS135...


My GP gun has 7 mm bearing - confirmed, Modify modular ger set for 7mm bear. fit perfectly.

I have a new 9,6V battery, and i dont want Li-po. I also have a new GP M160 motor. What is AOE?

Polycarb with metal tooth. I dont want too high rof anyway....

Approx how much BBs u shot with your current setup? If everything's done right, a metal toothed PB should last quite a while. If you experience premature wear on the gears, especially on the early teeths, it's a sign that you'll need better AOE.

If you're using Systema Silent PH, then you'll need to get the sorbopads which is specially meant to be used with the Silent PH.

With a M135 spring, you should be getting at the very minimum 450fps with 0.2g and 363mm barrels, otherwise, you're having major leaks. My stock springed AnK SPR MOD2 shoots at 480fps with a tight bore.

Not sure bout the Modular gearsets, but bearings are never meant for heavy springs. Bushing's the way to go.

AOE = Angle Of Engagement
*Note: When you do your AOE mod, make sure you shaved the 2nd and 3rd tooth as well to avoid premature engagement.

For ROFs, it's the combination of motor and voltage/amp supplied. You may have the motor (no exp with the G&P M160), but if the voltage/amps supplied is insufficient, you still don't get the ROF. This is especially true for heavy spring applications. From what I read, there are people that gets pretty good results when they pair two packs of 9.6v parallel. But you'll need a huge battery location for that.

I've been using the super cheap JG red piston with metal teeth on mine, no problem. Again, it can stand up to M140 spring rate. Ofcourse, with proper mods done to it.

Deepfire polycarb piston body with titanium coated piston tooth is good too, but pricey.

Best of luck with your project.

If its with in your budget I recommend adding and STS.

http://www.v2fix.com/

I already have these...

About bearings / bushings for gears...
I have Mofidy Modular Smooth gear set TORQUE (21,6:1) for V2 7mm mechabox, but not sure if they use bearings or bushnig, but on the back side of the gears packing is recommendation to use for M120-M140 springs. I suppose Prometheus M135 should be fine...
I mounted it in to my gun yeasterday. It works fine, even my GP M120 motor can handle it without difficulties with sufficient ROF, but I dont like the sound it makes. I assume it is becouse reinforced reverse latch and bevel gear which has more "teeth" then original from gp (had only 2) so it makes clicking sound when I spin the gears with my fingers. Motor does spin it much faster and it makes quite loud and annoying sound. Dose anybody have simmilar experience??

Where can I buy a sorbo pad for systema silent piston head?

Which reinforced gearbox for 8mm bearings (kanzen ceramic) would you recommend?
I am planning to change gp 7mm gearbox and modify smooth modular gears as I am unhappy with it....

So I bought Kanzen 8 mm beraings and Modify Torus 8mm gearbox, but unfortunatelly these bearings are much thicker then standard ones and it doesnt fit my lower reciever. I am wasting money for high end airsoft upgrade and I am more and more dissapointed. My gun is still not working because many incompatibility issues.

MODIFY also makes ceramic 8mm bearings:
http://www.airsoftparts.ca/store2/in...oducts_id=1372

To avoid the incompatibility issues, try to stick to one brand. I know the heartaches of trying to make guns with the best possible parts from a dozen manufacturers; unfortunately it is an exercise in frustration. I stick to MODIFY, Prometheus, or Systema.

As Skruface said above.

You cannot buy the "BEST Brand" for each part and put it together and expect it to work. Each manufacturer has different standards and Quality processes and in some cases different design philosophies on "X" part, which may not be 100% compatible with other parts.

I don't like Systema compression components, I prefer modify, prometheus and TM over prometheus. However it's easy to mod and fix the compression system of the gearbox so the brand isnt all that important.

To give you some examples of where I gained some performance by consolidating brands.

I switched my systema air nozzle to prometheus to match my prometheus neo hopup, gained 25 FPS, no tweaks to the air seal on either setup it was good on both setups.

On the P90 switched from a Systema air nozzle to a TM air nozzle and gained 30 FPS with M110 spring.

Go visit airsoftmechanics.com Their is excellent discussion on brand compatability. People running RIOTSC gears will not use modify shells because the bushing/bearing holes are not on TM specs.

I group components into 2 categories. Keep all the components within a working category or system the same brand.

Gears/shell/bearing/bushing
compression system (PH,Cylinder, Cylinder head, nozzle, Tappet, hopup unit)

I have RIOTSC gears, so which bearings/ bushings are compatible with them?? Kanzen 8 mm ceramic bearings fit without any problems.
Wondering if another investments of 35$ to modify ceramics bearings worth the money.
Maybe steel bushnigs would make the same job? I am not planning to have a high ROF gun. Just slightly stronger spring.
Which b/b would you recommend (thinner than kanzen to fit GP body)?