Specna SA-E11 Edge modifications help

[Rob360]

Hi All,

I'm new to airsoft, but wanted to modify the SA-E11 becasue I didn't realise when I got it that the barrel was 300mm long and was full length inside the silencer.  I wanted to replace the silencer with a shorter tracer unit.  So to achive this, I took the silencer off and measured the barrel lenght that protrudes out the outer barrel, 93mm.  I ordered a ZCI 6.02mm bore, 200mm long, stainless barrel.  The original is 6.03mm bore.  The rifle is fitted with a M100 spring.  Getting around 320fps using .20 on standard barrel.  After swapping the barrel over, i'm getting around 265fps.  As this seemed quite steep of a drop I put the original barrel back and it's back to normal.  Only the barrel was changed, bucking, nub and hop all same.

Does anyone have any advise on getting the power back up?  I'd like to keep the shorter barrel so I can use the tracer unit for CQB, but also as a backup for woodland play. 

Thank all.

 

[Pseudotectonic]

Shorter barrel lower FPS is normal because the BB has a shorter "runway" for acceleration before exiting the barrel

Solution is get a stronger spring to compensate, and/or use heavier BBs to partially recover some joules

 

[Sewdhull]

Stiffer spring and better airseal will give you more.

My mp5 barrel is 229mm gives 420fps on a .2 with an xt 120 spring

Can't say how accurate my chrono is tho

 

[Rob360]

Thanks guys, what spring would you recommend?  Currently has M100.  Glad I don't need to do something with the cylinder volume or gearing. 

 

[Pseudotectonic]

Hold on, are you chronoing with the hop all the way off? In case it was turned up and decreased your FPS by accident

 

[Rob360]

Hop completely off on testing for both barrels.

 

[Skara]

To achieve optimal results you will have to fuck around with voluming

For a bodge, I guess slap the supplied 120 spring in there and give it a go.

Won't be pretty, but again it's a bodge.

I do recommend you do things correctly, it'll preserve your internals and up the overall performance of the gun.

Specna gearboxes aren't the strongest so correct voluming will avoid premature breakages (as of now the piston impacts when the BB has long left the barrel, which means that it'll dump its whole energy onto the cylinder head, which in turn transfers it to the front of the gearbox).

You could also knock a few teeth off the sector to bleed some extra air volume.

 

[Pseudotectonic]

to keep things simple, say you want about 330 FPS for UK sites, 330/265 = 1.25

so I would say m115 is a safe bet and once you switch to .28s it will settle at about the joules you want (330 equivalent)

 

[Sewdhull]

If you need more energy in a shorter barrel your only way of getting getting more is a harder push, but you won't need the same volume of air.

Do you know what cylinder you have, in respect of the porting?

I've dropped 25fps by taking one of the spring bearings out.

I'm pretty sur I'm over volumed, there's not of a pop from the barrel

 

[Rogerborg]

One thing, are the indexing slots for the C-clip on the barrels at the same distance from the rear? Is the barrel and bucking securely seated in the hop unit?  There are no real standards in airsoft, and fractions of a mm differences can have radical results on airseal (or feeding). 

 

[Rob360]

To achieve optimal results you will have to fuck around with voluming

For a bodge, I guess slap the supplied 120 spring in there and give it a go.

Won't be pretty, but again it's a bodge.

I do recommend you do things correctly, it'll preserve your internals and up the overall performance of the gun.

Specna gearboxes aren't the strongest so correct voluming will avoid premature breakages (as of now the piston impacts when the BB has long left the barrel, which means that it'll dump its whole energy onto the cylinder head, which in turn transfers it to the front of the gearbox).

You could also knock a few teeth off the sector to bleed some extra air volume.

What would you recommend to do to do it correctly, I don't want to destroy the gearbox.

If you need more energy in a shorter barrel your only way of getting getting more is a harder push, but you won't need the same volume of air.

Do you know what cylinder you have, in respect of the porting?

I've dropped 25fps by taking one of the spring bearings out.

I'm pretty sur I'm over volumed, there's not of a pop from the barrel

I have no idea on the internals of the gearbox,  I found this on the internet about what's inside it:

[SIZE=9pt]reinforced polymer
piston.[/SIZE]

[SIZE=9pt]– aluminum, sealed nozzle[/SIZE]

[SIZE=9pt]– aluminum, double sealed cylinder head[/SIZE]

[SIZE=9pt]– aluminum, double sealed piston head with bearings[/SIZE]

[SIZE=9pt]– a spring guide with bearings[/SIZE]

[SIZE=9pt]– a set of steel gears[/SIZE]

[SIZE=9pt]– 8mm ball bearings[/SIZE]

One thing, are the indexing slots for the C-clip on the barrels at the same distance from the rear? Is the barrel and bucking securely seated in the hop unit?  There are no real standards in airsoft, and fractions of a mm differences can have radical results on airseal (or feeding). 

I checked the slots on the original and new barrels, the slots matched great.  Both barrels with the same bucking fit superb in the same hop unit.

 

[Dan Robinson]

Plus one for being careful with springs - I think me putting in a stronger spring was the final curtain for my Specna C12 gearbox recently, along with an 11.1v battery.

 

[ak2m4]

Ideally you should fit a 1/2 cylinder.

 

[Rob360]

Ideally you should fit a 1/2 cylinder.

I'm really not familiar with the gearboxes yet, are all cylinders the same size, just ported differenlty for different barrel lengths?  Is that all i'd need to change to compensate for the smaller barrel? 

 

[Sewdhull]

Yes they are the same size.

Ported cylinders can/will reduce energy if they are ported closer to the head

A stiffer spring is used to compensate if necessary 

 

[Pseudotectonic]

If you get a 1/2 ported cylinder, you won't increase the FPS to the previous levels, all the 1/2 cylinder is doing is theoretically reduce the air volume to match the shorter barrel i.e. reducing the theoretical turbulence flow theoretically affecting the BB after it exits the barrel theoretically (in reality I doubt there is any observable difference)

So you still need to get a stronger spring to compensate the lost FPS

 

[Rob360]

Thanks for all the replies. I've learnt a lot, now to order a stronger spring and cylinder and have a play

 

[ak2m4]

I'm really not familiar with the gearboxes yet, are all cylinders the same size, just ported differenlty for different barrel lengths?  Is that all i'd need to change to compensate for the smaller barrel? 

You'll most likely need to experiment a little with different springs, however it's worth trying what you have to start with if you just swop out the cylinder.  Not all M100 springs are equal (you don't say what brand yours is).  The ones you often receive with stock guns are poorer quality, some brands use stronger springs in order to compensate for poor compression/airseals. 

Perhaps a M110 together with a 1/2 cylinder good place to start.  Message me and I'll sort you out.