Maximum spring for gel blasters


I ordered a guarder sp130 spring from ebay. I wonder if it will break a plastic gearbox or a nylon gearbox.

What’s the maximum spring strength (roughly in terms of diameter only) for the gen9 or any other gel blasters?

Which spring breaks the plastic gearbox and which one breaks a nylon one?

Im thinking of getting the guarder sp110 spring, which according to an ■■■■■■■ forum can give you around 360 fps.

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I think from alittle reading is that 1.3 springs put a fair amount of load on a nylon gearbox. Any higher then 1.3 and youd blow a gearbox. Not sure if im right but theres someone here that can explain it better

I reckon 1.3 is the limit if you want thing to be accurate and reliable. If you are after a bruising hit at 10m and not worried after that and like fixing things then go higher.
I put a 1.4 in my gen 9 and the upgraded motor wouldnt pull the spring back.
I have settled on a 1.3 equal spring and seems to work good.
I have a nylon shell. Metal gears. Metal plunger. O rings. Brass nozzle. Shimmed and bearings


Forgot to say thats at 7.2v.
I tried 11.1 and that worked with the 1.4 un equal but cracked the clear housing after 3 mags.
Thats when i went with metal everything and nylon box.
The guy that built it for me said to stick with 7.2v and the only thing i will have to change are the o rings every few months.
He has been building and upgrading blasters for 3 years so I will stay at 7.2v. If i ever wont more rate of fire i will go with a mosftet.

@Matth1000 well said thats for adding detail :smile:

No dramas, happy to help.
Dont want people thinking that bigger is always better.
At the end of the day they are are just a plastic toy that we are modding to 3 and 4 times the pressure that they normally take.
Hopefully we get ■■■■■■■ in this country soon and we can ditch plastic and start talking 500fps and 80m instead of 250fps and 30m.
Check out Low Guido Chop Shop on youtube.
One of his latest videos is him puttting a metal ■■■■■■■ box into a blaster.
U might be able to go to a bigger spring then but the limits of the gel ball come into play. As they are going over 300fps they start to deform and then they go wherever they wont. They are only accurate if they remain round.
Thats why I try and keep mine to about 260-280 fps on 7.2v.
Packs a punch, accurate and reliable.
I have shot a 370fps custom build using ■■■■■■■ parts and it sounds like it was going to shake apart in my hand. Also couldnt hit a coke can 15m away. It would dent 1mm metal though but at the indoor cqb field i use would be illegal due to the 280fps limit.

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Great info guys. I been waiting the answers for a month now posted on Reddit. Now using the Well M4 clear shell, chucked 1.3 (not the stock spring) but after a few games the front side lower cracked. Now stick with 1.2. Cheers

No probs. Happy shooting

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Thank you guys. Looks like Ill be sticking to stock spring now on my clear plastic gearbox for now.

I chucked a 1.4 unequal in my scar v2. as my gearbox is nylon with a chi Hai high torque motor, shs 13:1 gears. 11.1v 1800mah lipo battery and alot more spent way too much on that badboy lol ($250-300) in mod but I found the cunt was punching too hard the gel balls exploded coming out the barrel and I’ve got the mad 7mm extra hard Millie’s from ausgel so dropped it back to 1.2 unequal and been sweet since

1.3 will crack an acrylic box…

iv been thinking of casting an outer case from alloy and clean it up with a dermal tool.
some of those CNC made gear box cases from alloy would hold up sweet, along with SS cylinder ,Alloy piston, alloy plunger, Metal gears and an adjustable hop up should give most M4’s plenty of punch.

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A 1.3 spring is the best one to use for accuracy, without loosing too much velocity.
Since I changed my 1.4 spring to a 1.3 in my custom M4, the accuracy is way better, should have done this long ago…
Unfortunately, the gel balls do not perform too well with too much velocity, way different to ■■■■■■■.

Little trick with milkys I do.
I grow them to full size and left in the fridge over night seems to give consistent balls (lol), And then if you want to go a step further put them in the freezer to chill them with out freezing gives em more sting and hold up to higher velocity.

haha I know that feeling all too well. lol another trick with milkies is to spray a couple squirts lol of isoprop to the chilled distilled water. mix it before dropping your balls in. lol be sure the iso- water is heavily diluted. so I normally do 2-2.5L of chilled distilled water, 2 squirts iso and leave in fridge until needed.

im assuming 1.3 spring your running is unequal spring. as I did the same with my scar dropped a 1.4 unequal and even with burst fire the first 2-3 had mad impact and accuracy but the other 2 that followed went everywhere but straight so toned it back and much better accuracy

I ran a 1.4 in my stock gen 8 box as a joke just to see how long it’d last. Did some accompanying mods to get it to a decent point (cast gears and a “high torgue” unbranded motor from wish) and it lasted like 5 games until we pulled it apart to find that the only thing that had started to give way were the bearing housings which had some hairline fractures. Rebuilt everything into a fresh stock box and put a 1.5 in and it ran for like 3 games till it shot the rail off of the plunger. Gearbox had no damage from it at all.

For J9 I have started to use the nylon housing, gren o/ring, 1.25 spring with 11.1V bat and keeped the nylon gears. getting 260/280, no fails yet.

if only I got that lucky. I upped the battery and piston and it cracked with 20mins

Gezz if only I could get that luck @Mr.milkman my first j9 broke in 5 magazines :joy::joy: