[j_f_oko]

The install went off without a hitch...this mechbox is a dream to work on. I installed the following:

Systema duracon bearing piston head
Systema bearing spring guide
Systema advanced polycarb piston
Guarder enhanced polycarb tappet plate
Deepfire cylinder
Deepfire nozzle
Hurricane Aero advanced cylinder head (didnt fit have to order something else)

With the exception of the cylinder head all parts have exactly the same dimensions.

However after i got everything put back together and tried to test fire i got a half cycle out of it and the piston was stuck at the back of the cylinder and the fuse disintegrated, i had remembered reading some threads about such problems on here before so i checked for some remedies and came up dry. After installing a new fuse, i tried a few more tricks and different batteries but still the same result. I disassembled and reassembled the mechbox at least 5-6 times, checking and rechecking things and swapping parts in and out between the new and old and this is what i found.

With the bearing piston head you're losing some spring space because of the bearing assembly, which is also true for the bearings on the spring guide, so when used together there may not be enough space for full spring compression. Since i wanted the new piston and piston head more than the spring guide i tried just using the new piston assembly and the old spring guide so i would only be losing spring space from one end. No go. But if I use the old piston and the bearing spring guide it works fine, but they both take up the same amount of extra space...still trying to figure that one out. The only thing i can think of is that it has to do with the piston itself because it is a really tight fit sliding the spring into the new polycarb piston and requires some finesse to get it all the way in, whereas its fairly loose when using the old one, maybe the tight fit is hindering the springs compression enough that its stalling the mechbox.

Now, with all of that out of the way i left it as is and just set the new piston assembly aside for now and am happy that my gun works with the few upgrades i was able to get working. Most of the info i've provided is here so that if anyone has any additional insight into my issues they can please let me know. But my main question is this:

Are there springs that differ that much in length that i will be able to fit both the piston assembly and spring guide without any issues? Remeber to keep in mind that the diameter of the spring as well as the length may be contributing to the issue. I have done some searching and from what i've found it sounds like a systema spring should work with these mostly systema parts that i've installed (makes sense since they're all designed to systema's specifications) or so the manufacturer would have you believe. Can anybody verify?

I want to have very similar performance to what i have now, the stock spring is fairly hot which i like, but i dont want to sacrifice longevity of mechbox parts for the sake of fps (anymore than it already is). I would like to keep it at around 365-385 fps. So short version... any spring recommendations for a slightly shortened and narrowed spring chamber that will provide my desired velocity?

I know there are tons of springs out there but not having hands on experience with them makes it difficult to know if they'll fit.

Hope the info i've provided is sufficient, because its a long post. And i'm looking foreward to getting some feedback.

Thanks.