G&P M4 upgrade to fps 420

[drjimmy]

Originally Posted by kudykam

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

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.

[Skruface]

Originally Posted by kudykam

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.

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.

Originally Posted by kudykam

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...

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

Originally Posted by kudykam

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

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.

Originally Posted by kudykam

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?

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.

Originally Posted by kudykam

Would you recommend to change hop up rubber??

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.

Originally Posted by kudykam

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..

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.

Originally Posted by kudykam

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...

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.

Originally Posted by kudykam

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...

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.

[kudykam]

Originally Posted by Skruface

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.

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.

Originally Posted by Skruface

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.

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...

Originally Posted by Skruface

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.

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.

Originally Posted by Skruface

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.

New one added to the basket...

Originally Posted by Skruface

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.

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

Originally Posted by Skruface

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.

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

[Skruface]

Originally Posted by kudykam

According to chart Prometheus MS120 is the same strangth as my PDI 170%. Where is the improvement?

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.

Originally Posted by kudykam

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.

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.

Originally Posted by kudykam

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...

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

Originally Posted by kudykam

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.

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

[yuhaoyang]

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.

[kudykam]

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...

[kudykam]

Originally Posted by yuhaoyang

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.

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

[Skruface]

Originally Posted by kudykam

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...

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.

[kudykam]

Originally Posted by Skruface

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

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...

[yuhaoyang]

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.

[kudykam]

Originally Posted by yuhaoyang

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?????

[yuhaoyang]

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

[kudykam]

Originally Posted by yuhaoyang

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....

[kudykam]

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.

[Skruface]

Originally Posted by kudykam

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?

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.

Originally Posted by kudykam

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.

I have no experience with either of those supressors.