Shaving 5-6fps off an AEG

[AshOnSnow]

Currently got a Guarder SP100 in my M4. With the tightbore fitted it's adding roughly 11% velocity onto the spring estimate, and shooting at 355 consistently. I need to shave a few fps off, but by my calculations, going down to an SP90 - which is estimated for 280fps - means it'll only shoot 310 as a maximum, and I don't really want to lose so much.

I've seen an "Element M95" spring which seems to be between the two, but either discontinued and nobody has any left, or just nobody has any plain and simple.

Is there a Guarder SP95? Or similar?

 

[HighTower94]

You could compress your spring fully over night, that will drop it down at least 10 fps

 

[Sitting Duck]

What bb's are you using ?

is your hop correctly adjusted ?

0.25's or 0.28's or 0.30's

if you are using a heavier bb like 0.25 or 0.28 and have the hop slightly increased for this weight

then it should just scrape under 350fps when chroning on 0.20's at the 0.28 setting

Most sites accept this hop being set for a slightly heavy weight when chrono on 0.20's

(nobody wants to keep messing about with more/less hop just to chrono on lighter 0.20's)

BUT must use 0.20's at the chrono or you are trying to directly cheat chrono

other options are:

pre-cock the gun on compression and leave overnight

shim/space the hop slightly away from gearbox using a thin 11mm ID shim say 0.5mm thick

(this would reduce the seal at lips and slight leak/lips blowing will reduce the fps a little)

in say 3-6 months the spring may fade & remove the shim

Similar thing can be done by a few layers of electricians tape at front of box or something

(you are basically reducing the effectiveness of the nozzle sealing on bucking lips to lower fps a smidge)

Or you can open her up for 5 to 6 fps which tbh is a PITA and most likely you will lose some of that once stuff beds in

TBH I'd set the hop up for say 0.28's and get her firing sweet

then plop a few 0.20's down the mag manually or speed loader - chrono with 0.20's @ .28 hop setting

should be under 350fps and most sites will allow this providing the 0.20's are not going into orbit asap

Or stick some tape/shim the hop forward a tiny bit - don't go nutz or mag might not clip into hop feed tube

Or leave her overnight pre-cocked should drop it ok

PITA to tear down a gun for 5-6fps & the fps will drop eventually

the fps won't improve/increase over time like fine wine

 

[AshOnSnow]

What bb's are you using ?

is your hop correctly adjusted ?

0.25's or 0.28's or 0.30's

if you are using a heavier bb like 0.25 or 0.28 and have the hop slightly increased for this weight

then it should just scrape under 350fps when chroning on 0.20's at the 0.28 setting

Most sites accept this hop being set for a slightly heavy weight when chrono on 0.20's

(nobody wants to keep messing about with more/less hop just to chrono on lighter 0.20's)

BUT must use 0.20's at the chrono or you are trying to directly cheat chrono

other options are:

pre-cock the gun on compression and leave overnight

shim/space the hop slightly away from gearbox using a thin 11mm ID shim say 0.5mm thick

(this would reduce the seal at lips and slight leak/lips blowing will reduce the fps a little)

in say 3-6 months the spring may fade & remove the shim

Similar thing can be done by a few layers of electricians tape at front of box or something

(you are basically reducing the effectiveness of the nozzle sealing on bucking lips to lower fps a smidge)

Or you can open her up for 5 to 6 fps which tbh is a PITA and most likely you will lose some of that once stuff beds in

TBH I'd set the hop up for say 0.28's and get her firing sweet

then plop a few 0.20's down the mag manually or speed loader - chrono with 0.20's @ .28 hop setting

should be under 350fps and most sites will allow this providing the 0.20's are not going into orbit asap

Or stick some tape/shim the hop forward a tiny bit - don't go nutz or mag might not clip into hop feed tube

Or leave her overnight pre-cocked should drop it ok

PITA to tear down a gun for 5-6fps & the fps will drop eventually

the fps won't improve/increase over time like fine wine

Click to shrink...

Down with techs, but I will assume ASG Blaster .20s, with the hop all the way in. I'll ask them to compress it for a few hours - maybe when they start tomorrow, chrono it later in the afternoon to see if it's down at 350.

 

[Sitting Duck]

we chrono with 0.20's

but most run with 0.25's for a bit more range/accuracy

so pick up a bag of say G&G 0.25's dial it in and you should be fine next time it is chrono'd on 0.25's

give say 3 months & that extra few fps will have gone

or plop in a shorter barrel but tbh I'd see if you can just scrape the gun under the 350fps than mess about any more

 

[Hangtight]

Is that on your chrono or a site chrono? My Xcortech consistently reads 8 fps lower than the one at CSW, and 5fps higher than the one at a local shop.

Leaving the spring compressed for a couple of days should calm things down a bit, or adjust the hop for your preferred weight ammo and chrono with that. Then use one of the comparison charts to see if you're still running hot. A quick fix is take the bearing off the spring guide, or take the one out of the piston and replace it with a plastic spacer you can adjust to the right length. Losing a bit of piston weight (the bearing) can drop the fps a little.

 

[AshOnSnow]

Is that on your chrono or a site chrono? My Xcortech consistently reads 8 fps lower than the one at CSW, and 5fps higher than the one at a local shop.

Leaving the spring compressed for a couple of days should calm things down a bit, or adjust the hop for your preferred weight ammo and chrono with that. Then use one of the comparison charts to see if you're still running hot. A quick fix is take the bearing off the spring guide, or take the one out of the piston and replace it with a plastic spacer you can adjust to the right length. Losing a bit of piston weight (the bearing) can drop the fps a little.

Click to shrink...

I don't know, I've not chronoed it, I dropped it off down with the techs.

 

[Sitting Duck]

I don't know, I've not chronoed it, I dropped it off down with the techs.

Click to shrink...

that means they will park it pre-cocked overnight maybe space the hop if req

Then charge you £50 parts n labour for it all 

nah - kidding, reckon they can scrape it under without another major strip down

shove in std hop/barrel - that would drop it a smidge if ya put a tbb in there

 

[AshOnSnow]

that means they will park it pre-cocked overnight maybe space the hop if req

Then charge you £50 parts n labour for it all 

nah - kidding, reckon they can scrape it under without another major strip down

shove in std hop/barrel - that would drop it a smidge if ya put a tbb in there

Click to shrink...

Well they've had it since last week. It's very confusing. I bought it along with a Laylax 6.03 and Guarder SP100 spring from Taiwan gun. Chrono sheet from taiwangun says downgraded to under 350 and has some readings around 340 ish. I sent it straight down to the techs when it arrived. They called me later and said that they'd changed the barrel and got it shooting 350/351. When I went in to pick it up, it turns out that TaiwanGun had been helpful and already installed the tightbore and SP100 (i didn't realise because I'd received a spring and a barrel in a Guarder SP100 packet and a Laylax 6.03mm tube. They must have just used the packaging to put the original M120 spring and 6.08 barrel in. So now the techs have put the tightbore back in, apparently it's shooting 355 with the hop in.

Not sure why it's chronoing at 355 when TaiwanGun has it around 340. Unless, they first downgraded the gun, chronoed it, then installed the SP100 and Tightbore (not sure why they'd do it in that order).

At the moment, I've just been trying to figure out what's happened when and where. I haven't even pulled the trigger yet, but apparently it's 5fps over, and they're telling me the only realistic option is for them to install an M90 which will shoot 330-340. Not sure how that works out if an SP100 is shooting 355, surely the difference would be bigger...

 

[Hangtight]

Depends on the make of spring sometimes. I've got a stock JG 100 and that shoots 325, and a Modify M100 that shoots 342.

 

[Sitting Duck]

Jeez....

Rather than go into further

As Hangtight said - is there a bearing spring guide in there ?

Is there a piston bearing or spacer inside the actual piston ?

Take the damn thing out

It is all about spring compression/power

A spring say m100 pushing exactly 328fps perfectly can be tweaked 10-15 fps more/less

heck even 30-45 fps more/less if the spring compresses more less

A bearing spring guide Vs a std spring guide is about 4mm extra spring compression (15fps aprox)

Same $hit as a piston head bearing 15 fps or about 5mm spacer

10mm spacer - the chunky f*cker found in crap cheap guns weighing 7.5gms about 9mm will add 30fps

(though maybe extra weight will mean only 25fps)

Barrel lengths will alter fps or creep - a ROUGH guide is perhaps 100mm shorter barrel will drop about 40fps

(this is exact like for like 400mm std barrel to 300mm std barrel - a tbb will increase fps over a wider/std barrel)

Armed with this crap, the tech could remove the spring bearing guide as Hangtight said and you would be easily under 350fps

If this was removed already then the bearing or spacer inside the piston could be removed/replaced

(again this would compress the spring less and thus provide a smidge less power)

OR

Depending on piston's rack - ShortStroke the sector gear just one tooth losing say 15fps per tooth

you can only ShortStroke if your piston's rack has more than just one metal tooth on it

(you must have at least one tooth metal that it slips/releases the piston from eg: 3 or 7 or all metal teeth)

The same can be applied in reverse - slightly more spacings to compress the spring further

Though you need to be very careful to check a 10mm spacer or above doesn't bottom out on spring guide at full stroke

So the very same m100 spring producing exactly 328fps every single shot every time

could be made to shoot 300 to 355fps in the exact same gun

and this is before looking at changes to barrel etc....

Now this may be a very very daft question...

I presume the tech already corrected the AoE ?

I'd be beyond shocked if they hadn't already but again if they haven't then this will knock of say 10fps once corrected

To lose just 5 or 6 fps is not difficult at all

it is more a f*cking pain to do really as we know very likely it will decrease a little itself over time anyway

I'd see if you can scrape it under as is

or

as Hangtight said - replace a bearing spring guide for a std one if you have to open it up

or reduce the spacing inside the piston

Yes you could fit a lower spring, close it up and find: F*ck only 300fps now

at least you know that spring is just a smidge over for sure than take a chance on another spring

If the spring is an irregular one - then if it is fitted back to front - reverse it to the correct way

The tighter coils at one end should be placed at spring guide

imho if you place the tighter coils at piston head you get an extra 10fps aprox

I have tested quite a few irregular springs both ways in an APS UAR - brill spring checker btw

and these are my findings - you get an extra 10fps if you fit an irregular spring ar$e about face

(just in case the spring was fitted incorrectly then turn it around but be careful you don't gain a further 10fps)

PITA but always a bit risky when trying to so close to the max possible fps

which tbh is over rated as TM's shoot 300fps and perform miles better than my slightly hot SRC Dragon @ 357fps

(but fps limits is what sites go by so we work within those guidelines I guess)

Really tbh you don't wanna spend more time/money pi$$balling about to just knock off a little over a few fps

The more you f*ck with stuff the more agro or work you can be making for yourself in the end

Within 3 months seals will drop a smidge or spring might fade & it will drop anyway

any slight bodge to decrease the fps can be rectified like shim the hop

park the gun pre cocked and chrono in the morning

if little joy leave until the end of the day or another night

or shim it to slightly blow the seal on bucking lips at hop

(f*ck taking it apart again for little over a few fps)

If the techs are looking to open the box up then ask them a simple question....

Have they opened up the box themselves and/or have checked or corrected the AoE ???

If they haven't opened the box up or can't confirm for sure the AoE is correct

then I would lay money the AoE is still not properly corrected and that should be addressed first

well yeah remove/replace spring guide is easier but not all guns have bearing spring guide

and the jury is out on this cyma metal M4 coz cyma use at least 2 maybe 3 different v2 boxes

and still they seem to use a v3 spring guide in their v2 boxes - mostly std non-bearing spring guide

I keep saying I'd scrape or park the gun overnight

if after a day or two no joy then I would check spring guide and/or correct AoE

You should not need another spring imho - just go with what is in there

correct AoE tolose a smidge of stroke or if that bastid metal spacer is n there replace/remove it

 

[AshOnSnow]

Jeez....

Rather than go into further

As Hangtight said - is there a bearing spring guide in there ?

Is there a piston bearing or spacer inside the actual piston ?

Take the damn thing out

It is all about spring compression/power

A spring say m100 pushing exactly 328fps perfectly can be tweaked 10-15 fps more/less

heck even 30-45 fps more/less if the spring compresses more less

A bearing spring guide Vs a std spring guide is about 4mm extra spring compression (15fps aprox)

Same $hit as a piston head bearing 15 fps or about 5mm spacer

10mm spacer - the chunky f*cker found in crap cheap guns weighing 7.5gms about 9mm will add 30fps

(though maybe extra weight will mean only 25fps)

Barrel lengths will alter fps or creep - a ROUGH guide is perhaps 100mm shorter barrel will drop about 40fps

(this is exact like for like 400mm std barrel to 300mm std barrel - a tbb will increase fps over a wider/std barrel)

Armed with this crap, the tech could remove the spring bearing guide as Hangtight said and you would be easily under 350fps

If this was removed already then the bearing or spacer inside the piston could be removed/replaced

(again this would compress the spring less and thus provide a smidge less power)

OR

Depending on piston's rack - ShortStroke the sector gear just one tooth losing say 15fps per tooth

you can only ShortStroke if your piston's rack has more than just one metal tooth on it

(you must have at least one tooth metal that it slips/releases the piston from eg: 3 or 7 or all metal teeth)

The same can be applied in reverse - slightly more spacings to compress the spring further

Though you need to be very careful to check a 10mm spacer or above doesn't bottom out on spring guide at full stroke

So the very same m100 spring producing exactly 328fps every single shot every time

could be made to shoot 300 to 355fps in the exact same gun

and this is before looking at changes to barrel etc....

Now this may be a very very daft question...

I presume the tech already corrected the AoE ?

I'd be beyond shocked if they hadn't already but again if they haven't then this will knock of say 10fps once corrected

To lose just 5 or 6 fps is not difficult at all

it is more a f*cking pain to do really as we know very likely it will decrease a little itself over time anyway

I'd see if you can scrape it under as is

or

as Hangtight said - replace a bearing spring guide for a std one if you have to open it up

or reduce the spacing inside the piston

Yes you could fit a lower spring, close it up and find: F*ck only 300fps now

at least you know that spring is just a smidge over for sure than take a chance on another spring

If the spring is an irregular one - then if it is fitted back to front - reverse it to the correct way

The tighter coils at one end should be placed at spring guide

imho if you place the tighter coils at piston head you get an extra 10fps aprox

I have tested quite a few irregular springs both ways in an APS UAR - brill spring checker btw

and these are my findings - you get an extra 10fps if you fit an irregular spring ar$e about face

(just in case the spring was fitted incorrectly then turn it around but be careful you don't gain a further 10fps)

PITA but always a bit risky when trying to so close to the max possible fps

which tbh is over rated as TM's shoot 300fps and perform miles better than my slightly hot SRC Dragon @ 357fps

(but fps limits is what sites go by so we work within those guidelines I guess)

Really tbh you don't wanna spend more time/money pi$$balling about to just knock off a little over a few fps

The more you f*ck with stuff the more agro or work you can be making for yourself in the end

Within 3 months seals will drop a smidge or spring might fade & it will drop anyway

any slight bodge to decrease the fps can be rectified like shim the hop

park the gun pre cocked and chrono in the morning

if little joy leave until the end of the day or another night

or shim it to slightly blow the seal on bucking lips at hop

(f*ck taking it apart again for little over a few fps)

If the techs are looking to open the box up then ask them a simple question....

Have they opened up the box themselves and/or have checked or corrected the AoE ???

If they haven't opened the box up or can't confirm for sure the AoE is correct

then I would lay money the AoE is still not properly corrected and that should be addressed first

well yeah remove/replace spring guide is easier but not all guns have bearing spring guide

and the jury is out on this cyma metal M4 coz cyma use at least 2 maybe 3 different v2 boxes

and still they seem to use a v3 spring guide in their v2 boxes - mostly std non-bearing spring guide

I keep saying I'd scrape or park the gun overnight

if after a day or two no joy then I would check spring guide and/or correct AoE

You should not need another spring imho - just go with what is in there

correct AoE tolose a smidge of stroke or if that bastid metal spacer is n there replace/remove it

Click to shrink...

And AoE means?

 

[Sitting Duck]

And AoE means?

Click to shrink...

Angle of Engagement:

http://www.airsoftsociety.com/forums/f10/adjusting-aoe-23129/

basically, removing 2nd tooth (1st tooth is chunky one called pick up tooth)

and slightly reducing the height of 3rd tooth a slither where/if needed

moving the piston back a smidge 2-3mm so sector's 1st tooth engages perfectly

std guns out of box don't do this and if you can imagine...

as the sector's first tooth meets the pick up tooth further foward,

it kind of pushes up as it draws back piston

over time or at speed the large chunky pick up tooth can snap off (no $hit)

(but usually at speed and probably weak piston material)

I've known rental guns to still not have AoE corrected for yonks

but have seen weak pistons snap even when corrected but taking the pi$$

moving the piston back a smidge, removal of first tooth etc....

this ensures the sector tooth & pick up mesh better simply drawing the piston straight back

the aim is the sides of the teeth touch & this check should be done with spring installed

cheapo fix is a 20mm diameter 2to 3mm thick washer super glued onto existing cylinder head

proper fix is remove the hard as brick rubber on std cylinder head, fit a sorbothane pad on there

then top off with a 2mm neoprene (rubber) washer to protect it

sorbo is squishy to help absorb impact, but gets hammered so protect with durable neoprene

On average the piston needs to move back about 2mm to 3mm

the 2nd tooth removed completely & light file on the 3rd perhaps

When this is performed the stroke is reduced slightly and fps drops about 10 to 15 fps

Normally we do this AoE & at the same time fit a bearing spring guide which roughly cancels it out

The bearing spring guide increases the spring compression to offset the fps loss from AoE

Well technically it isn't quite 101% offset coz the piston's stroke is still reduced slightly

BUT you get the idea and should be fine for most people unless the cylinder's port or volume was low

Anyway - correcting AoE should drop say 10fps

RANT TIME:

Gun Manufacturers....

WTF - Don't they f*cking do this anyway I'll never know ??

WTF - don't they fit o-ring nozzles & bearing spring guides ??

(ok maybe/maybe not bearing spring guides but stuff like AoE is pennies)

WTF - don't most guns get assembled better in the first place is beyond me

Yeah I know - slap it together in a Far Eastern Sweat Shop banging out stuff per hour by piece workers

but still most gun manufacturers could up their game a little

RANT OVER

 

[AshOnSnow]

Just picked it up, they told me to put a bottle of BBs through it and the spring would wear down a few fps since it's new, so I picked up some devil .28s. Hopefully tomorrow when I've fired through them all, it'll be within site limits.

 

[Sitting Duck]

Just picked it up, they told me to put a bottle of BBs through it and the spring would wear down a few fps since it's new, so I picked up some devil .28s. Hopefully tomorrow when I've fired through them all, it'll be within site limits.

Click to shrink...

I think it is on the cusp

yes it could settle a smidge but might take a month or two

If you set the hop for 0.25's or the 0.28's lifting correctly

then hopefully & quite likely when it is chrono'd on 0.20's (must use 0.20's at chrono or you are trying to cheat)

it should just be under 350fps

The only possible fly in the ointment is your local site's chrono

As Hangtight says chrono's can vary a little

My Gen x3200 "seems" to be fairly accurate to my local 350fps and the Mall's chrono limit of 340fps

However you local chrono could be showing 350 as 350 or a deviation of 347 or 353fps

Also some sites may or may not be ultra ultra strict on a few fps over

"just go easy up close" some sites have said on occasions

Not getting into the the ethics of this - a site limit is a site limit at the end of the day

just saying some might and I say "might" apply a tiny whisker of discretion perhaps

Me personally I'd rather the person not the gun rows back a bit of power

(not saying for a sec I want a DMR shooting me a point blank but I don't like dicks going overkill on everyone at 330fps either)

At the end of the day the site's limit and the site's chrono is what matters

That is what they go by, their insurance, their safety, so if they say NOPE - too hot then that is final I'm afraid

(No flames or grief please - we all know we should be at 349.99fps or under but doubt if I would rip gun open tbh for 5/6fps)

Reckon the 0.28's once the hop is set should chrono on 0.20's under 350fps

and in a months time the fps will start to decrease slightly anyway

End of the day until you run it through your own site's chrono you won't know for sure

it could chrono @ 340 if there is a deviation between shop/site chrono

or worse still it could show 365-370 at ya local site's chrono and you are f*cked - lol

(oops now I got him really really worried)

Nah - I reckon you will be fine, end of the day only one way to find out or suck it & see as they say

fingers crossed & happy shooting

 

[Hangtight]

Just be aware that some sites chrono with the ammo you use on the day and then use a chart to calculate that back to fps with 0.2g BBs. That's too stop people exploiting joule creep.

 

[AshOnSnow]

I think it is on the cusp

yes it could settle a smidge but might take a month or two

If you set the hop for 0.25's or the 0.28's lifting correctly

then hopefully & quite likely when it is chrono'd on 0.20's (must use 0.20's at chrono or you are trying to cheat)

it should just be under 350fps

The only possible fly in the ointment is your local site's chrono

As Hangtight says chrono's can vary a little

My Gen x3200 "seems" to be fairly accurate to my local 350fps and the Mall's chrono limit of 340fps

However you local chrono could be showing 350 as 350 or a deviation of 347 or 353fps

Also some sites may or may not be ultra ultra strict on a few fps over

"just go easy up close" some sites have said on occasions

Not getting into the the ethics of this - a site limit is a site limit at the end of the day

just saying some might and I say "might" apply a tiny whisker of discretion perhaps

Me personally I'd rather the person not the gun rows back a bit of power

(not saying for a sec I want a DMR shooting me a point blank but I don't like dicks going overkill on everyone at 330fps either)

At the end of the day the site's limit and the site's chrono is what matters

That is what they go by, their insurance, their safety, so if they say NOPE - too hot then that is final I'm afraid

(No flames or grief please - we all know we should be at 349.99fps or under but doubt if I would rip gun open tbh for 5/6fps)

Reckon the 0.28's once the hop is set should chrono on 0.20's under 350fps

and in a months time the fps will start to decrease slightly anyway

End of the day until you run it through your own site's chrono you won't know for sure

it could chrono @ 340 if there is a deviation between shop/site chrono

or worse still it could show 365-370 at ya local site's chrono and you are f*cked - lol

(oops now I got him really really worried)

Nah - I reckon you will be fine, end of the day only one way to find out or suck it & see as they say

fingers crossed & happy shooting

Click to shrink...

When they Chrono the 355, it was with the hop fully engaged putting max spin on the BBs - flying way up into the air, but reducing the overall FPS as they leave the gun. With the hop set straight, it fires off 365.

 

[Sitting Duck]

When they Chrono the 355, it was with the hop fully engaged putting max spin on the BBs - flying way up into the air, but reducing the overall FPS as they leave the gun. With the hop set straight, it fires off 365.

Click to shrink...

Ahhh - then that is kinda pushing it to squeeze under chrono....

Not being funny but the shop should of made the call/judgement

possible AoE could of done it or nearly enough...

TBH - set hop roughly halfway and see how it shoots

turn gun on its side 90 degrees and you should see bb's curving left/right indicating hop is on/working

fine tune it for range/flight etc.....

think you might wanna leave it precocked overnight but still might notbe effective enough to drop it down much

Bloody annoying coz I know or lay money that AoE most likely hasn't been corrected & bet it still has a metal spring spacer

damn it can't find a pic but this shows what a lump is used to mount piston head on...

that chunky bit of metal is still used on some guns SRC and Cyma's I have found

compresses spring by quite a bit 9mm & weighs 7.5gms too

springs used to have a hook that clipped into this chuncky mount

but cyma don't use/need the hook coz their springs are not hooked on like they used to

but maybe you can see them using this mofo spacer in this pic...

no need to compress the bloody thing so much imho

 

[AshOnSnow]

Also need to work out how to tighten the hop gears - they're wayyy too loose, almost to the point of jiggling out if I try a couple seconds burst. 

 

[Hangtight]

The gear with the cam that acts on the hop arm should have a spring steel retainer on the back side of the shaft where it emerges from the other side of the hop. The intermediate gear should have a flange on the face against the hop which stops it moving past the adjuster wheel, which should have a screw through the middle holding it to the hop. If it's just the adjuster wheel that's loose then taking it off and putting a smear of silicone on the back, allowing it to fully cure before reinstalling it can help add a bit of friction between the wheel and the hop. Some M4 hops have an O ring behind the adjuster to do exactly the same job.

Alternatively... ASG/ Lonex hop unit. Proper job.