Sig 552 FPS upgrade

[scoobabob94]

Ok, so I plan on significantly upgrading my sig 552 (I know this is shunned upon because its a hard upgrade but I want a gun thats unique and performs well). So my target is to hit around 400 fps (I want to get as close to 400 as possible without going over) using .25 gram bb's. I plan on using high torque up parts to both increase ROF and because I plan on using a 9.6 volt 600 MaH battery, so increased battery life is a plus. The list of parts I plan on using are as follows:
-KM inner barrel
-Eagle force 1300S (will those motor properley fit in the sig 552?) If not I will go for the Systema super torque up medium motor
-Systema Super Torque up flat gears
-Systema spring guide with bearings
-Systema polycarbonate piston
-I don't know what type of piston head to use, I was thinking a systema silicon piston head with bearings to reduce stress on the gearbox, but would an aluminum one or a silent one be better?
-Oiless bushings
-I plan on leaving the cylinder and head stock, is this a problem?

So basically I want to know if theres anything drastic that I'm forgeting, or if my idea won't work all together. Also would upgrading the air nozzle and tappet plate be beneficial? Oh ya I almost forgot, what spring would put me in the 400 fps region with .25's, the PDI 150% or the PDI 170%, or any other spring for that matter. I'm sorry for such a lengthy post, I'm just curious as to whether or not this would work, thank you.

[ILLusion]

The Sig552 uses a medium length motor. Eagle Force doesn't make something appropriate to fit. Systema does.

I recommend increasing the length of your inner barrel if you want to be able to easily reach your 400fps mark, otherwise you'll have to install a stronger than average spring just to hit 400fps. Keep in mind that if you increase your barrel length, you might have to change your cylinder.

Piston head, get whatever you want - the v3 gearbox can take the shock of an aluminum piston head. And plus, your shots with an aluminum piston head will sound better.

Generally, velocity ratings are made with 0.20g BBs. If you want to hit 400fps with 0.25g BBs, you're looking at 450fps springs such as a Guarder SP130, Systema M130, M140, Prometheus MS140SP, MS150SP, PDI 190%, KM 140M or possibly even stronger if you don't plan on increasing your barrel length. These are all really really heavy springs. Your rate of fire will severely suffer if you keep that mini battery. Trying to make such a short barreled gun shoot such a high velocity won't be impossible, but it's going to be expensive and you're going to have to decide on velocity or rate of fire. With super torque up gears, torque up motor and a spring this heavy with a mini battery, expect really low rate of fire and trigger response time.

Other than that, the upgrade plan looks fine if you understand and accept the losses associated with it.

[scoobabob94]

Thank you very much, I may have to shoot for a little bit lower fps then so I can still maintain a decent ROF.

[longshot]

Illusion upgraded my Sig-552 a few months ago.
I am shooting at around 350fps with .20BB and around 320fps with .25bbs.
The parts I used for my upgrade was very basic...Guarder metal bushing, Guarder spring guide, Area 1000 piston, Guarder aluminum piston head, Prometheus MS100 spring.
The big catch is that I am using a 9.7V 1700mah battery on a battery box, mounted to the 20mm side rail. This set up gives me a great ROF and the reliability that I am looking for on an AEG. Also keep in mind of your "battle field' conditions and the style of your play. In my case, win or lose I always like to edge closer to my opponents.

[scoobabob94]

Its good to know that upgrading it is actually doable. My field can be pretty wide open at points, and using a stock AEG just hasnt been cutting it, I can see people from pretty far away but I cant hit them, unfortunately most of the people that I play with have upgraded guns so it makes it tough.

But anyways, would 400 fps with .2 gram bb's be achievable without going lower than the stock ROF? If not I'll probably shoot for something around 350.

yes.

reinforced standard ratio gears and a 9.6v battery could have you with even faster ROF

[ILLusion]

But your mini battery, even at 9.6v wouldn't last too long pushing a spring that heavy with standard ratio gears.

If you aim for 350fps, you would be much better off.

[scoobabob94]

ok, so it seems like I'm going to have to aim for 350 fps with .2 grams, I'll still be happy with that as it's still much better than stock, thank you all very much for your help.

[millartime]

Just my 2c worth as I to had the same problem with my Sig this is what I did.

metal bushings.
promethius ms100 spring
started with a 9.6v but now have a 10.6 from here http://www.onlybatterypacks.com/show...temID=11067.27

this fits in the front battery tray with a little mod but I do suggest getting gears as to the R.O.F is crazy and will kill your stk gears at some point I have yet to do so and it still goes strong I shoot around 340-350 right now but plan on a spring upgrade to maybe a ms120 some will disagree with me but this is working for me right now so far so good...Clint

[scoobabob94]

how is that battery working for you? I've heard bad things about those ones

[millartime]

so far so good I have had it for about 6m and no problems the only thing is it's nihm ver nicad you can't peek a nihm it's a little more delicate but again I personally have had no trouble with it...

[scoobabob94]

Ok so here is my new game plan, I will be shooting for about 350 fps while using the 10.8 v battery that millartime recommended. Since I no longer have to worry about battery capacity I wont have to worry about torque up gears or a new motor right? I can just get normal reinforced gears? Also one thing about that battery, I know it says you have to cut off the locktabs for the side rail, is there anyway that you can reatach the side rail with this battery installed?

[millartime]

I just removed it and reattached it to the bottom rail drill 2 small holes and your back in business it's not perfectly straight but for a light or laser it doesn't need to be...

[ILLusion]

Originally Posted by scoobabob94

Ok so here is my new game plan, I will be shooting for about 350 fps while using the 10.8 v battery that millartime recommended. Since I no longer have to worry about battery capacity I wont have to worry about torque up gears or a new motor right? I can just get normal reinforced gears? Also one thing about that battery, I know it says you have to cut off the locktabs for the side rail, is there anyway that you can reatach the side rail with this battery installed?

You might want to go with torque up gears just to slow down your ROF. with a 10.8v battery, your magazines might not even be able to keep up with the battery.

[scoobabob94]

But if I used a 9.6 v 1400 mAh battery I'd be fine without the torque up? Thanks again Illusion, your a big help