Can't get fps over 320fps

[Pewpewpetie]

Hi, currently working on a new build. It's a specna sa-go1 (E&C v2 gearbox). I've tried most things and still can't get it past 320fps even with guarder sp100 and near perfect gearbox seal, full metal rack, double oring nozzle etc, running a 407 madbull python with specna rotary hop, maple 60°bucking with omega nub. I originally thought it may be nozzle to hop leaking so tried my prowin with zci out of my dmr and still no difference. I literally have no ideas left, I've tried ported and non ported cylinders aswell. 

[L3wisD]

Sounds like you've covered a lot of bases with all the parts.

 

Are we sure it's definitely an SP100 and not an incorrectly bagged SP90?
@ak2m4 - was it guarder springs that came in incorrectly rated recently?

[Pewpewpetie]

35 minutes ago, L3wisD said:

Sounds like you've covered a lot of bases with all the parts.

 

Are we sure it's definitely an SP100 and not an incorrectly bagged SP90?
@ak2m4 - was it guarder springs that came in incorrectly rated recently?

Yes, also tried shs m110 and still won't budge past 320, it's strange as consistency is near perfect 318/320

[AlphaBear]

I had a similar problem with a V2 gearbox AEG... totally drove me nuts as I had covered all bases... turned out to be the spring and a not so very clean inner barrel... I had  an M100 spring firing M90 fps just so you know.. sometimes even the manufactures can cock up!

[Pewpewpetie]

36 minutes ago, L3wisD said:

Sounds like you've covered a lot of bases with all the parts.

 

Are we sure it's definitely an SP100 and not an incorrectly bagged SP90?
@ak2m4 - was it guarder springs that came in incorrectly rated recently?

Last I fiddled with it was this morning with a non ported Cylinder and the 407mm barrel and still the same. 

1 minute ago, AlphaBear said:

I had a similar problem with a V2 gearbox AEG... totally drove me nuts as I had covered all bases... turned out to be the spring and a not so very clean inner barrel... I had  an M100 spring firing M90 fps just so you know.. sometimes even the manufactures can cock up!

Ive tried shs m110 which in my dmr gives me 420fps and yet in this build still only 320

[AlphaBear]

The cylinder (type a) matches the barrel so it may not be that... I'm wondering if the gears are actually pulling the piston back fully as needed? Check the AOE and check for dodgy piston wear and gear wear. 

[Pewpewpetie]

11 minutes ago, AlphaBear said:

The cylinder (type a) matches the barrel so it may not be that... I'm wondering if the gears are actually pulling the piston back fully as needed? Check the AOE and check for dodgy piston wear and gear wear. 

I'll be doing that tonight when I get home and try to upload some pics.

[Stevo4345]

Check there's no restriction in your cylinder head, flap of loose Sorbo pad maybe? 

[Pewpewpetie]

3 minutes ago, Stevo4345 said:

Check there's no restriction in your cylinder head, flap of loose Sorbo pad maybe? 

I'll check later, just very odd to have such a consistent fps. 

[AlphaBear]

This will make a great video for Luke from Negative Airsoft if we can't help you solve this one!

What lube have you used in the cylinder..? Wash the cylinder out with soapy water (degrease it), do the same with the piston and then suberlube ceramic grease very very small amount... @ak2m4 sells a wee syringe of it.. To me it sounds as though the piston isn't moving fast enough to push out the fps...and check for a cracked nozzle too..and a worn tappet plate...

[Pewpewpetie]

4 minutes ago, AlphaBear said:

This will make a great video for Luke from Negative Airsoft if we can't help you solve this one!

What lube have you used in the cylinder..? Wash the cylinder out with soapy water (degrease it), do the same with the piston and then suberlube ceramic grease very very small amount... @ak2m4 sells a wee syringe of it.. To me it sounds as though the piston isn't moving fast enough to push out the fps...and check for a cracked nozzle too..and a worn tappet plate...

Negative is the best, been watching his vids since he started. I use very small amount of halfords spray silicone grease. The thing that I find most odd is the consistency of the fps. If there was air leaks etc I would be seeing a wide variance in fps( I assume) 

[Sitting Duck]

Blowing at bucking lips, not making sufficient seal etc...

 

Could be poor or incorrect/incompatible nozzle/hop

Tight nozzle shoulder or tilted gearbox that causes to rub/restrict return

Tappet not fully returning to seal 101% either needs sanding at front or catching on sector's axle

Plus...

Usual hop unit shifting forward when mag inserted causing hop/nozzle poor seal

(tape in magwell & ensure spring on hop pushing it backwards etc...)

 

Do the three hand test of hop /barrel removed manually fitted against gearbox

with BB & chrono - will take a few attempts no doubt but FPS goes up when treating

If so then poor alignment/compatibility etc...

 

Sounds like it just doesn't quite seal against lips, lightly nozzle so lightly kisses the bucking lips so when fires any extra power just blows at the seal and there is your FPS loss

 

I say it sounds like blowing at lips assuming spring(s) are correct

 

But either hop shifting, poor compatibility of nozzle/hop or nozzle length, restriction on nozzle movement/final return position, poor alignment if gearbox tilted or out of whack when all assembled - nozzle rubbing as it slides in/out of hop blah blah blah...

 

The only way is diagnose each individual component and how it operates

Or

Go back to stock parts & retest, then carefully check/measure/compare each component you replace with other parts seeing how efficiently they operate

 

The moment you start changing and replacing stuff without double/triple checking EVERYTHING, then you leave yourself wide open for headaches if not serious migraines

 

Rebuilding a box from scratch is involved even more checking from scratch on every component as you can't quite compare stuff like stock nozzle lengths, if after market selector plate works 101% or exact same as stock one, if a replacement cut off lever fully resets on the trigger trolley, if the wanky flat speed trigger jumps off the trigger trolley at full pull etc....

(Fuck me there can be LOADS & LOADS of compatibility issues changing shit over)

 

Hence it is easier to change just a very few stock components only when really needed and paying very very very close attention to detail comparing length of nozzles and full efficiency of the replacement parts you fit

 

Even then, after all this you still get issues in the assembly if stuff shifts like tightening gearbox/stock tube that tilts gearbox up at front or hop unit tries to shift forward when mag is inserted etc....

 

What nozzle did you fit - if SHS the single o-ring is better imho as the nozzle front completely rounded without the tiny nicks to prevent possible BB suck on the double o-ring nozzle

 

Nozzle lengths vary, M4 is "usually" around 21.45mm but other makes/models use shorter ones, uses a SHS M4 nozzle in say an ICS split M4 gearbox ICS rotary hop and you will have feed issues coz ICS M4 nozzle used is shorter

 

All this TM compatible BS is at best compatible -ish and shit always needs to be checked very very thoroughly unless you have a good supply of paracetamol or if you can't won't check shit then only replace parts with genuine components from your gun's manufacturer type of thing

(even then poor batches or poor assembly can occur)

 

Nozzle not sealing on bucking lips is my guess but could any number of reasons or a culmination of factors causing issues

Which is down to you or somebody to go through & methodically test/check stuff blah x 3

 

More info and pics might help too, if you have a bearing spring guide or not, bearing spacer in piston - all of which adds more spring compression/power or lowers if removed

Correcting AoE lowers FPS by say 15fps but is usually replenished if installing a bearing spring guide

Spacer or bearings inside piston can be like compressing spring a further 2 or 3 teeth, so can vary by another 30-40fps etc...

Plus different gun's/barrels mean a m100 spring could shoot 300fps to say 360fps in another on full piston stroke - let alone volume or short stroking 

55 minutes ago, Pewpewpetie said:

Negative is the best, been watching his vids since he started. I use very small amount of halfords spray silicone grease. The thing that I find most odd is the consistency of the fps. If there was air leaks etc I would be seeing a wide variance in fps( I assume) 

 

If the lips are blowing then anything past 320 is expelled by pissing at lips

 

Sounds weird but does happen in some cases, almost what you push out the lips start to blow at that xxx figure coz the seal is poor and at that point excess power blows the seal

 

But yeah send it off to Luke might save you a lot of agro (and my fingers)

[AlphaBear]

If you do send it off to Luke @Armourpiercing, let us know coz we wanna see the video and all that colourful language...  

[Pewpewpetie]

47 minutes ago, Sitting Duck said:

Blowing at bucking lips, not making sufficient seal etc...

 

Could be poor or incorrect/incompatible nozzle/hop

Tight nozzle shoulder or tilted gearbox that causes to rub/restrict return

Tappet not fully returning to seal 101% either needs sanding at front or catching on sector's axle

Plus...

Usual hop unit shifting forward when mag inserted causing hop/nozzle poor seal

(tape in magwell & ensure spring on hop pushing it backwards etc...)

 

Do the three hand test of hop /barrel removed manually fitted against gearbox

with BB & chrono - will take a few attempts no doubt but FPS goes up when treating

If so then poor alignment/compatibility etc...

 

Sounds like it just doesn't quite seal against lips, lightly nozzle so lightly kisses the bucking lips so when fires any extra power just blows at the seal and there is your FPS loss

 

I say it sounds like blowing at lips assuming spring(s) are correct

 

But either hop shifting, poor compatibility of nozzle/hop or nozzle length, restriction on nozzle movement/final return position, poor alignment if gearbox tilted or out of whack when all assembled - nozzle rubbing as it slides in/out of hop blah blah blah...

 

The only way is diagnose each individual component and how it operates

Or

Go back to stock parts & retest, then carefully check/measure/compare each component you replace with other parts seeing how efficiently they operate

 

The moment you start changing and replacing stuff without double/triple checking EVERYTHING, then you leave yourself wide open for headaches if not serious migraines

 

Rebuilding a box from scratch is involved even more checking from scratch on every component as you can't quite compare stuff like stock nozzle lengths, if after market selector plate works 101% or exact same as stock one, if a replacement cut off lever fully resets on the trigger trolley, if the wanky flat speed trigger jumps off the trigger trolley at full pull etc....

(Fuck me there can be LOADS & LOADS of compatibility issues changing shit over)

 

Hence it is easier to change just a very few stock components only when really needed and paying very very very close attention to detail comparing length of nozzles and full efficiency of the replacement parts you fit

 

Even then, after all this you still get issues in the assembly if stuff shifts like tightening gearbox/stock tube that tilts gearbox up at front or hop unit tries to shift forward when mag is inserted etc....

 

What nozzle did you fit - if SHS the single o-ring is better imho as the nozzle front completely rounded without the tiny nicks to prevent possible BB suck on the double o-ring nozzle

 

Nozzle lengths vary, M4 is "usually" around 21.45mm but other makes/models use shorter ones, uses a SHS M4 nozzle in say an ICS split M4 gearbox ICS rotary hop and you will have feed issues coz ICS M4 nozzle used is shorter

 

All this TM compatible BS is at best compatible -ish and shit always needs to be checked very very thoroughly unless you have a good supply of paracetamol or if you can't won't check shit then only replace parts with genuine components from your gun's manufacturer type of thing

(even then poor batches or poor assembly can occur)

 

Nozzle not sealing on bucking lips is my guess but could any number of reasons or a culmination of factors causing issues

Which is down to you or somebody to go through & methodically test/check stuff blah x 3

 

More info and pics might help too, if you have a bearing spring guide or not, bearing spacer in piston - all of which adds more spring compression/power or lowers if removed

Correcting AoE lowers FPS by say 15fps but is usually replenished if installing a bearing spring guide

Spacer or bearings inside piston can be like compressing spring a further 2 or 3 teeth, so can vary by another 30-40fps etc...

Plus different gun's/barrels mean a m100 spring could shoot 300fps to say 360fps in another on full piston stroke - let alone volume or short stroking 

 

If the lips are blowing then anything past 320 is expelled by pissing at lips

 

Sounds weird but does happen in some cases, almost what you push out the lips start to blow at that xxx figure coz the seal is poor and at that point excess power blows the seal

 

But yeah send it off to Luke might save you a lot of agro (and my fingers)

Really appreciate you took the time to write that. How would I check if it's blowing from bucking lips? I can test the mag moving hop forward by placing a bb in hop chamber and firing whilst holding hop back against gearbox through mag well. but not sure how to check bucking lips. The nozzle is from a specna edge, I'd say exactly same measurements but I don't have a digital measuring device to be that accurate

[Sitting Duck]

1 hour ago, Pewpewpetie said:

Really appreciate you took the time to write that. How would I check if it's blowing from bucking lips? I can test the mag moving hop forward by placing a bb in hop chamber and firing whilst holding hop back against gearbox through mag well. but not sure how to check bucking lips. The nozzle is from a specna edge, I'd say exactly same measurements but I don't have a digital measuring device to be that accurate

 

when nozzle is fully forward at front of gearbox...

placing the hop unit up against the gearbox you should feel slight resistance when the two meet but still have a gap of aprox 1mm before they fully meet flush...

ergo in use the nozzle doesn't just kiss or lightly touch the bucking lips, but have a little extra pressure to maintain the seal between the nozzle edge & lips of bucking under pressure/use

 

However - just coz they might work out of the gun OK

doesn't mean when installed and in use the two components maintain their seal

as M4's especially the hop unit is free floating rather than firmly fixed like say AK's

 

so there is a chance on some instances, on some guns, some hops/nozzle combo's - even some mags

the hop can shift forward and you lose a great seal that allows the leak to occur & fps drop etc....

 

you normal have a spring on hop unit to push back to gearbox/nozzle but that assumes that everything is working properly within the tolerances blah blah blah

I've bloomin' covered this last week or so....

 

 

or an o-ring or two...

 

 

just stuff to keep hop in place and help maintain the seal from hop trying to shift forward

other crap like tape in magwell but say at front of receiver to keep mag/hop towards gearbox/nozzle

(plus some mags can slightly shift shit forward more than others in rare cases)

 

but this is still guesswork as to exactly where or what the exact issue is

but feel it is very likely due to a leak at bucking lips from poor seal/pressure when nozzle meets bucking

 

but this actual reason might due to wrong nozzle length or not returning properly

 

your best bet is to send it off to luke coz if I could predict things that accurately - well I should start doing the lottery again

 

alas it is still just a possible stab in the dark or very dimly lit room & if you got no way of measuring crap

then yeah send it off to luke to get it sorted & running sweet

[Pewpewpetie]

1 hour ago, Sitting Duck said:

 

when nozzle is fully forward at front of gearbox...

placing the hop unit up against the gearbox you should feel slight resistance when the two meet but still have a gap of aprox 1mm before they fully meet flush...

ergo in use the nozzle doesn't just kiss or lightly touch the bucking lips, but have a little extra pressure to maintain the seal between the nozzle edge & lips of bucking under pressure/use

 

However - just coz they might work out of the gun OK

doesn't mean when installed and in use the two components maintain their seal

as M4's especially the hop unit is free floating rather than firmly fixed like say AK's

 

so there is a chance on some instances, on some guns, some hops/nozzle combo's - even some mags

the hop can shift forward and you lose a great seal that allows the leak to occur & fps drop etc....

 

you normal have a spring on hop unit to push back to gearbox/nozzle but that assumes that everything is working properly within the tolerances blah blah blah

I've bloomin' covered this last week or so....

 

 

or an o-ring or two...

 

 

just stuff to keep hop in place and help maintain the seal from hop trying to shift forward

other crap like tape in magwell but say at front of receiver to keep mag/hop towards gearbox/nozzle

(plus some mags can slightly shift shit forward more than others in rare cases)

 

but this is still guesswork as to exactly where or what the exact issue is

but feel it is very likely due to a leak at bucking lips from poor seal/pressure when nozzle meets bucking

 

but this actual reason might due to wrong nozzle length or not returning properly

 

your best bet is to send it off to luke coz if I could predict things that accurately - well I should start doing the lottery again

 

alas it is still just a possible stab in the dark or very dimly lit room & if you got no way of measuring crap

then yeah send it off to luke to get it sorted & running sweet

Thanks alot for your time. Ive put it all back to stock. Too late to test now as kids asleep. I'll report back in the morning with my findings. 

[Pewpewpetie]

11 hours ago, Sitting Duck said:

 

when nozzle is fully forward at front of gearbox...

placing the hop unit up against the gearbox you should feel slight resistance when the two meet but still have a gap of aprox 1mm before they fully meet flush...

ergo in use the nozzle doesn't just kiss or lightly touch the bucking lips, but have a little extra pressure to maintain the seal between the nozzle edge & lips of bucking under pressure/use

 

However - just coz they might work out of the gun OK

doesn't mean when installed and in use the two components maintain their seal

as M4's especially the hop unit is free floating rather than firmly fixed like say AK's

 

so there is a chance on some instances, on some guns, some hops/nozzle combo's - even some mags

the hop can shift forward and you lose a great seal that allows the leak to occur & fps drop etc....

 

you normal have a spring on hop unit to push back to gearbox/nozzle but that assumes that everything is working properly within the tolerances blah blah blah

I've bloomin' covered this last week or so....

 

 

or an o-ring or two...

 

 

just stuff to keep hop in place and help maintain the seal from hop trying to shift forward

other crap like tape in magwell but say at front of receiver to keep mag/hop towards gearbox/nozzle

(plus some mags can slightly shift shit forward more than others in rare cases)

 

but this is still guesswork as to exactly where or what the exact issue is

but feel it is very likely due to a leak at bucking lips from poor seal/pressure when nozzle meets bucking

 

but this actual reason might due to wrong nozzle length or not returning properly

 

your best bet is to send it off to luke coz if I could predict things that accurately - well I should start doing the lottery again

 

alas it is still just a possible stab in the dark or very dimly lit room & if you got no way of measuring crap

then yeah send it off to luke to get it sorted & running sweet

Problem solved. Not sure how to explain it but it was nozzle, basically the one I changed it for was exact same height but where they taper from widest part to thinnest part was different. The new one didn't have a long enough wider part, thus not making a complete seal. Thanks everyone for your time. Now chronoing 346/348 over 10 shots on 0.2g.

[AlphaBear]

Amazing and well done.... see something as simple as a nozzle makes all the difference....that reminds me I need another prommy one for another build but they ain't cheap... £30'ish for a NGRS bit of plastic.... !

[Pewpewpetie]

35 minutes ago, AlphaBear said:

Amazing and well done.... see something as simple as a nozzle makes all the difference....that reminds me I need another prommy one for another build but they ain't cheap... £30'ish for a NGRS bit of plastic.... !

I'm talking milimeters, but it made all the difference

[Adolf Hamster]

31 minutes ago, Pewpewpetie said:

I'm talking milimeters, but it made all the difference

 

such is the way with airsoft, tolerances are the key.

[Pewpewpetie]

6 minutes ago, Adolf Hamster said:

 

such is the way with airsoft, tolerances are the key.

Gets very frustrating at times but I love it at the same time

[Adolf Hamster]

3 minutes ago, Pewpewpetie said:

Gets very frustrating at times but I love it at the same time

 

indeed, it's one of the reasons a gun made of nominally very good parts might not perform so well. as duck says the best we can hope for is "compatible ish"

 

 

[Sitting Duck]

well done, fingers crossed & all that...

 

been there many many many times etc...

 

any small tiny tiny threads of knowledge or wisdom, I might have gained has been the direct result of fuck up after fuck up

and STILL weird shit happens at times even despite all the best planning & checking all shit twice over

 

fucking poxy toy gun shite at times - but live n learn as they say

 

[AlphaBear]

Even though these small things can sometimes frustrate the hell out of us, it's a bloody accomplishment when a plan cones together and one feels a sense of self satisfaction and achievement when you figure it out. Yes it's easy to send it off to a tech if you so wish but where's the fun in that? 

[ak2m4]

On 12/03/2020 at 14:31, L3wisD said:

Sounds like you've covered a lot of bases with all the parts.

 

Are we sure it's definitely an SP100 and not an incorrectly bagged SP90?
@ak2m4 - was it guarder springs that came in incorrectly rated recently?

 

Sorry only just seen this, been busy buying up the world's supply of SHS pistons 🙂

 

Guarder sp100's measure super high, around M110 power so 370 ish with 0.2g bb whilst the sp90 is generally spot on 310 ish with 0.2g bb.  I guess so many different countries with different power requirements this is what works for them.