Specna Arms Project Gun Logs

[MrTea]

Hi all.

Just wanted to drop in and ask if anyone ever replaced the handguard on any Specna Arms AEG with an aftermarket one? 

I've just received a used Nuprol Bocca series two handguard as they're nigh on impossible to find new in the tan/bronze anywhere. I disassembled my SA-C04 and attempted to thread the replacement Nuprol barrel nut on to find that it won't thread past half way on  meaning the outer barrel is loose and I cant fit the new handguard. I didn't want to force it on with an AR tool.

The threads on the Nuprol supplied barrel nut aren't in the best condition but according to the seller, it works fine on the AEG they had it on. In the mean time, I've ordered a brand new series two rail just to test a new barrel nut to see if that's the issue.

Are Specna Arms receiver threads different to the majority of AEGs that this handguard is probably made for?  Do I need to get a Specna arms produced handguard or just a different barrel nut? The threads on the receiver are a little chewed and paint missing but the original delta ring assembly still threads on tightly so they're not totally shot... Yet.

Pics to follow later today as I'm currently on the night shift.

Thanks in advance for any help.

 

[JimFromHorsham]

I just fitted a series2 bocca rail (12.5” black ) for someone to a WE GBBR , and it came with two barrel nuts one went straight on and the other barely a full turn so I assumed that was for AEG . Did neither of yours not come with two ? Or has the new one not turned up yet ? 
 

as for Specna , I fitted a HAO mk16 rail to mine with the aeg spec nut and it went on with no dramas at all .

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[Nick G]

I just fitted a series2 bocca rail (12.5” black ) for someone to a WE GBBR , and it came with two barrel nuts one went straight on and the other barely a full turn so I assumed that was for AEG . Did neither of yours not come with two ? Or has the new one not turned up yet ? 
 

as for Specna , I fitted a HAO mk16 rail to mine with the aeg spec nut and it went on with no dramas at all .

View attachment 103091

Thats weird, wonder if it's a nuprol thing. Ive fitted the Angry gun L119 A2 front rail to both a WE GBBR and an aeg and than only comes with 1 barrel nut. Might have used a single shim behind it on the GBBR's from memory but thats all I did. 

 

[JimFromHorsham]

Thats weird, wonder if it's a nuprol thing. Ive fitted the Angry gun L119 A2 front rail to both a WE GBBR and an aeg and than only comes with 1 barrel nut. Might have used a single shim behind it on the GBBR's from memory but thats all I did. 

airsoft innit ??‍

then add Nuprol into the mix .

 

[MrTea]

I just fitted a series2 bocca rail (12.5” black ) for someone to a WE GBBR , and it came with two barrel nuts one went straight on and the other barely a full turn so I assumed that was for AEG . Did neither of yours not come with two ? Or has the new one not turned up yet ? 
 

as for Specna , I fitted a HAO mk16 rail to mine with the aeg spec nut and it went on with no dramas at all .

View attachment 103091

Thanks for the reply. The used handguard only came with one barrel nut and I've been assured that it's the AEG one but you know how sellers are. Looking at pictures of the barrel nuts, they both look the same but I assume the threads are different.

The new handguard hasn't arrived yet. Should be posted tomorrow and probably arrive on Wednesday. Was just hoping people had some insight ahead of time.

I've seen those HAO MK16 rails and was tempted but I much prefer the look of the DD mk18 rail.

Thats weird, wonder if it's a nuprol thing. Ive fitted the Angry gun L119 A2 front rail to both a WE GBBR and an aeg and than only comes with 1 barrel nut. Might have used a single shim behind it on the GBBR's from memory but thats all I did. 

I've seen this quoted from a couple places during my googling about my issue.

 

[JimFromHorsham]

What you may find is the GBBR nut will fit both , and the AEG nut will only fit AEG .

 

[MrTea]

Updates with pictures. I've took pictures of the handguard where the barrel nut sits, a couple of the barrel nuts threads and one of the handguard plate which is particuarly battered.

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Not terribly bothered about the state of the handguard plate, can be changed with the new one that i've ordered if that new barrel nut fits but i'm impressed how they've battered it that much.

 

[Nick G]

That's seen some abuse ! 

 

[JimFromHorsham]

That's seen some abuse ! 

TBH it doesn’t look far off what I pulled from a box supposedly as new ?

 

[MrTea]

Well... after a couple hours dicking around with what is probably now my project or teching gun, the handguard is on! I tried both new barrel nuts to find that the GBBR barrel nut did exactly the same as the one the guy sent me so I think he's somehow forced it onto an AEG. The new AEG barrel nut that came needed backing off once or twice but threaded all the way down without issue. Due to the increased length of the handguard (over stock) I got lucky with a 1.2" barrel extention being the perfect length to let the flash hider sit just at the end of the handguard. I slapped a spare handstop and RIS rail covers on to see what it looked like.

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Now it's on, i've ran into a new, interesting, issue thats difficult to see from the pictures. The outer barrel is leaning/pulling to one side. It has zero movement up/down, just left to right. I already used a varying number of barrel shims to fix this issue with no luck. I'm now planning on a couple of options to fix this.

1. First, I could try using some padding/filler inside the handguard to essentially shim the outer barrel where it's least supported at the front.
   
2. Second, cable tie or wire shenanigans to fix the outer barrel in place.
   
3. Third, anything anyone else can suggest to fix the problem.
   

The gun is likely only going to be used in a semi-auto only indoors site. Testing on 7.4v LiPo shows that the gun is already pretty snappy but it's pretty loud and it looks like the gearbox sticker hasn't been cut. It probably needs a reshim/relube.

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Suggestions welcome.

I also now have a spare 7" Nuporl Bocca Series Two handguard if anyone wants to buy it.

 

[MrTea]

Took another couple of pictures to display what the issue is. I've tried adjusting how many barrel shims i've used to no avail. Someone on some long forgotten forum post suggested nipping up the grub screw on the outer barrel so I tried that. It's almost eliminated the wobble in the outer barrel but it's clear it's sitting off centre of the handguard. Aside from the cable tie method mentioned in this video i'm drawing a blank on what else to do.

Google brings up a couple results for barrel spacers for MK18 style handguards but they're out of stock almost everywhere or won't ship to the UK. Can't find any aliexpress wares for this either.

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[MrTea]

After a couple afternoons trying out different options between making spacers for the bolts of the handguard and tightening the bolts in a proper pattern I have accidentally fixed the issue by taking apart the outer barrel and reassembling it.

I'm not exactly sure why it fixed it but it has. The outer barrel is now pretty much dead center and has zero wobble. Not going to complain but it would have been nice if there was a clear and obvious issue causing it.

 

[MrTea]

Another afternoon of playing with the project gun and today I opened up the gearbox. The gearbox sticker was still intact. It had never been opened, ever.

The job today was re-shim, re-grease the internals of the gearbox, adding a Perun Hybrid V2, new inner barrel, bucking, nub and adding a functional sling-plate rather than the blank one that comes with the gun.

The Perun was a doddle to install minus a bit of dremelling required on a post inside the gearbox that blocked the trigger travelling all the way. Once that was dealt with, MOSFET was in quickly, tested and working.

Re-shimming the gearbox was a bit more troublesome. Had a couple of false starts with the shimming with one setup cycling halfway then locking up. Managed to get it right eventually. I probably should've got new bearings but totally forgot about it. For greasing the gears I used some Teflon grease designed for bikes as I didn't have time to get some LT2 grease. I used Silicone grease for the compression parts which are on their last legs. A new, upgraded, compression set should have arrived today but Royal Mail are on a go slow so they're getting here tomorrow. The current parts improved with new grease but they're still poor but don't have a chrono on hand to check how bad they are and how good it is after.

Reassembling the gearbox was a faff on, the issue being the tappet plate rather than the anti-reversal latch. The tappet plate wanted to keep jumping over the sector gear but was fixed with a long, small, flat screwdriver holding it down while I squeezed the top of the gearbox case on.

I added the new inner barrel and I thought it'd be a bit long (340mm) but it's the perfect length for my build. However, I have an issue with whichever factory makes/assembles the SA-C04. The grease/oil they use for the inner barrel/bucking STINKS of fish. I mean, not a little smell, it reeks! The bucking was well beyond it's expiry and went the journey to be replaced with a maple leaf Macaron 60 degree bucking and the nub was changed to a Prometheus flat nub. I cleaned the inside of the hop-unit the best I could with a cotton bud to remove the old oil/grease.

Once reassembled, I added the new sling-plate and put the the remainder gun back together. Programming the MOSFET was easy and with 3 levels of active braking and 4 of precocking, the piston is almost all the way to the rear and the trigger response is so fast.

Moving forward from here, i'm not sure where to go next. 13:1 gears? High torque motor? Brushless motor? Any and all advice/ideas appreciated here. I do think i'd go for a CNC/metal hop unit as the finishing on the Specna Arms one is poor as I had to clear off several sprues when changing the barrel & bucking. At the minute I have a new ambi charging handle in tan, dust cover and bolt plate arriving from AirsoftPro.cz to replace the worn/scratched/slightly rusted parts on the gun.

 

[MrTea]

Another few hours working on the gun today. New compression parts arrived from AK2M4 and what a huge difference they are compared to the old set. I wish I had a chrono on hand to test the before and after. Had a bit of trouble installing the flat trigger (also from AK2M4) as the body pin for the receiver would block the selector going to safe and would bind the trigger. Took about 30 minutes of slowly dremeling material away from the middle third of the pin until the issue was resolved.

Put back together and tested. Working flawlessly and feeds fine with the new compression parts. Cannot wait to get this out to a field.