[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.