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Brackit
Jan 23, 2019


Finished product first:


In 1954, George Sullivan founded Armalite and hired Eugene Stoner as his chief engineer. Together, they designed 14 unsuccessful rifles. The 15th one was okay, I guess. They quickly pawned it off to some horse company and forgot about it.

Having given away their golden goose, Armalite soon found themselves strapped for cash with nothing to sell. They had to design something new, without infringing on the patents they sold off. In 1963, they released the best modern rifle nobody wanted: the AR-18. This piston-driven, stamped steel assault rifle was destined for international markets, but it only really became popular with pissed-off Irishmen.

Fast forward to the 1970s and the British Ministry of Defense is looking to adopt a new bullpup service rifle, having already thrown away two perfectly good ones. They made several prototypes based on the AR-18 and Stoner 63, but rather than pay licensing fees to Armalite for the use of their intellectual property, the MoD gave them the single-finger salute, copied Stoner's homework, and continued on to produce the most reviled service rifle of all time: the SA80.

Today, in celebration of the great American tradition of reclaiming things from the British, I present to you: the SA-180.



This build is based on the Brownells BRN-180, an AR-18-ish upper that mounts to a standard AR-15 lower. It modernizes the AR-180 by adding a full length optics rail and slim keymod handguard. And of course, doesn't require a buffer tube. There were a few malfunctions with this upper during the first 100 rounds or so, all caused by short-stroking. However, I've been using Wolf .223, which is notoriously undergassed. Other users on this forum and elsewhere have also experienced issues, so I'll keep you posted on how this one holds up in the long-term. (I don't exactly have a ton of options anyway.)

The attached lower has a standard, mil-spec trigger group, which is operated using an electronic solenoid. The front pistol grip hides a tactile button switch and a 12V relay to energize the solenoid. A lithium-ion airsoft battery is held in the tube in front of the trigger, to power the whole system.



Most bullpups have lovely triggers. This one doesn't. The trigger pull is very crisp, and almost too light, even using the stiffest tactile button I could find.

Is that even legal? Yes! The ATF doesn't care how a trigger works, as long as it only fires one shot at a time. (Except for bump stocks and gat cranks, but whatever.) They clarified their position on electronic triggers (and many other fun things) in a Q&A letter from 2013. The barrel is 16 inches, and the extra long flash hider puts it over the 26 inch minimum overall length, making this not-an-SBR. The lower receiver is a normal, registered and serialized lower.

full letter

The optic is a Sig Sauer BRAVO3, which I selected in order to experiment with using a wide-angle, fixed power optic, instead of a LPVO or red dot and magnifier combo. For a $300 sight, the glass is remarkably clear, and it comes with nifty features like motion activation with auto-off, and a 5.56 BDC. Unfortunately, this build requires the optic to be mounted to the free-floated, quick detach handguard, instead of the receiver, which is going to affect accuracy. Nevertheless, my poor marksmanship and crappy ammo produced group sizes well below the strict military standard of 4 MoA.


The real kicker is the crazy-wide field of view: 52 feet at 100 yards. This is exceeded only by the BRAVO4 ($1,000) with 53 feet at 100 yards (and 4x magnification instead of 3x), and some Russian optics: the PO3.5x21P, PO4x17, and PO4x24P. The hope with this optic is that the wide FOV will help mitigate the tunnel-vision you get from magnified optics that makes close-range target acquisition more difficult. I've yet to bring this thing to a match, but we'll find out how that works eventually.


All of the custom parts were 3D printed in ABS and designed using FreeCAD in my spare time.

What other gun-stuff can you 3D print?

Useful things!



Stupid things!

These are all iron sights.

Don't tell New Jersey!


And yes, you can print those too. You just can't give them to anyone.


Overall, this has been a fun project, and I look forward to you all telling me I'm crazy for doing it.

Brackit fucked around with this message at 02:31 on Jul 5, 2019

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ThinkFear
Sep 14, 2007



Doing HK's job at a fraction of the cost

What's next for the project?

Baconroll
Feb 6, 2009


Very nice. If you want a real SUSAT optical sight to put ontop there are a small number of legitimate (i.e. not stolen from the military) surplus ones around but they will likely all have dead/dying tritrium.

The surplus ones I saw were all surplused by a British Police force about 10 years ago.

Theres also a small number of the cadet L98A1 version of the rifle in civilian hands in the UK - I'd guess substantially less than 100 (probably less than 20) and they are very rarely sold on.

Ironically part of rarity is because before the airsoft copies came along you had the real functional rifles being deactivitated for use in the movie/tv industry and being collected by the Walts. Deactivated guns were at the time selling for far more than the functional guns !

Brackit
Jan 23, 2019


ThinkFear posted:

What's next for the project?
Moving the battery to the back to improve the weight distribution and make the stock long enough to not need the long flash hider.

Shima Honnou
Dec 1, 2010

The Once And Future King Of Dicetroit



College Slice

Alternatively don't remove that XM flash hider at all because it owns.

This deserves a SUSAT but a fake SUSAT and not a real one.

Pursesnatcher
Oct 23, 2016



Grimey Drawer

Oh, I want to do this so bad. Shame minimum overall length here is 33 inches.

Somebody Awful
Nov 27, 2011

BORN TO DIE
HAIG IS A FUCK
Kill Em All 1917
I am trench man
410,757,864,530 SHELLS FIRED




Ugly as sin and at the same time.

Shaocaholica
Oct 29, 2002

Fig. 5E


This owns.

Captain Log
Oct 2, 2006

Captain Log posted:

"I AINT DYING! Choo choo motherfucker!"




I didnít know DeWalt made guns.

Baconroll
Feb 6, 2009


Pursesnatcher posted:

Oh, I want to do this so bad. Shame minimum overall length here is 33 inches.

Create an LSW version !

wheres my beer
Apr 29, 2004


Tryin' to catch me ridin' dirty


Fun Shoe

i have the strangest boner right now

wheres my beer fucked around with this message at 21:29 on Jul 4, 2019

Pursesnatcher
Oct 23, 2016



Grimey Drawer

Baconroll posted:

Create an LSW version !




Miso Beno posted:

i have the strangest boner right now

22 Eargesplitten
Oct 10, 2010

Certified Centrist Trash


This is cool as hell.

Thought: how much energy does the solenoid take, do you have any way of calculating that? I wonder if it would be possible to modify the recoil mechanism to generate power to charge the battery. Granted that wouldnít be a small undertaking since that would by necessity reduce the amount of energy available for the gun to cycle.

How has the durability been on those? We were just having a discussion in the tacticlol thread about the normal failure points of plastic versions.

Sorry if I missed it in the middle of all of the other cool stuff, how much does that weigh in at? If youíre willing to talk about the materials and print specs youíre using I would be extremely interested, but I understand if thatís more of a trade secret thing right now.

E: Thought for the sight situation: You've got a flat top rail on top of the receiver currently covered by a 3d printed rail cover, maybe print a gooseneck type thing that covers the top rail and extends up and over the handguard to mount the sight? Not sure what material you're using and I don't have Fusion 360 open right now or the inclination to model something right now but rigidity might be an issue. If so, you could try printing with holes down the length of the gooseneck portion and stick a thin CF rod down the length either with epoxy or by baking the gooseneck printed with a slightly under-sized hole so the hole expands, then running the rod down the hole while the printed part is still hot. That's assuming your material will return to the exact same shape after heating, I've never tried.

22 Eargesplitten fucked around with this message at 01:48 on Jul 5, 2019

Terrible Robot
Jul 2, 2010

FRIED CHICKEN


Slippery Tilde

This owns bones. I customized and printed all of the furniture (not the lower) for my AR build that I really need to post some day but this is next level. Great work!

Shaocaholica
Oct 29, 2002

Fig. 5E


I like how you care about FOV. I do at least for eye ergonomics. I thought about getting a Bravo4 for cheap but it looks really dumb. Iím fine with ACOGs which have a super wide FOV as it is. At least the 4x ones anyway.

You can always get a rail riser that spans the receiver and hand guard that should help with zero.

Brackit
Jan 23, 2019


22 Eargesplitten posted:

This is cool as hell.

Thought: how much energy does the solenoid take, do you have any way of calculating that? I wonder if it would be possible to modify the recoil mechanism to generate power to charge the battery. Granted that wouldnít be a small undertaking since that would by necessity reduce the amount of energy available for the gun to cycle.

How has the durability been on those? We were just having a discussion in the tacticlol thread about the normal failure points of plastic versions.

Sorry if I missed it in the middle of all of the other cool stuff, how much does that weigh in at? If youíre willing to talk about the materials and print specs youíre using I would be extremely interested, but I understand if thatís more of a trade secret thing right now.

The solenoid I'm using pulls about 35 watts when energized. The battery is a 1000 mAh 11.1v battery, so it's 11.1 watt-hours. If we assume one shot requires powering the solenoid for one second, we get a little over 1,000 shots per charge. If I wanted more, I'd swap out the mil-spec trigger for a lighter one and use a weaker solenoid.

In total, we shot about 25 rounds through that printed lower before coming to the conclusion that "yep, it works, and it's scary, and I don't want my face near it anymore". It was an experiment anyway, and 25 shots is enough for me to call it a success. That one was done in nylon, which should hold up better in the long run than ABS or PLA. It flexes a lot at the buffer tower, where you'd expect; it'll certainly break if you do push-ups on it. But, during firing, the bolt carrier extends into the buffer tube and keeps it from bending too far out of alignment with the upper receiver.

The bullpup weighs a lot! It currently comes in at 8.7 pounds empty, though to be fair, 1.4 of that is in the scope alone. Being a bullpup though, the weight is closer in to your body, so it's not too bad. All the parts are in ABS plastic, joined with the occasional M3 screw. None of them are really "load-bearing", so I didn't do anything fancy regarding high temperatures or acetone washing, just a few more wall lines and floor layers than usual.

At the moment, I don't plan on sharing the files for the bullpup. Not that I'm going to patent or sell any of this, or that it would be illegal to share them, I'm just not sure I'm ready to dip my toe in the murky waters of "distributing firearm blueprints over the internet".

Mr Fish
Nov 16, 2016


This is a freakin sweet gun. Having owned a regular AR-180 now I really need me a bullpup one.

22 Eargesplitten
Oct 10, 2010

Certified Centrist Trash


Brackit posted:

The solenoid I'm using pulls about 35 watts when energized. The battery is a 1000 mAh 11.1v battery, so it's 11.1 watt-hours. If we assume one shot requires powering the solenoid for one second, we get a little over 1,000 shots per charge. If I wanted more, I'd swap out the mil-spec trigger for a lighter one and use a weaker solenoid.

In total, we shot about 25 rounds through that printed lower before coming to the conclusion that "yep, it works, and it's scary, and I don't want my face near it anymore". It was an experiment anyway, and 25 shots is enough for me to call it a success. That one was done in nylon, which should hold up better in the long run than ABS or PLA. It flexes a lot at the buffer tower, where you'd expect; it'll certainly break if you do push-ups on it. But, during firing, the bolt carrier extends into the buffer tube and keeps it from bending too far out of alignment with the upper receiver.

The bullpup weighs a lot! It currently comes in at 8.7 pounds empty, though to be fair, 1.4 of that is in the scope alone. Being a bullpup though, the weight is closer in to your body, so it's not too bad. All the parts are in ABS plastic, joined with the occasional M3 screw. None of them are really "load-bearing", so I didn't do anything fancy regarding high temperatures or acetone washing, just a few more wall lines and floor layers than usual.

At the moment, I don't plan on sharing the files for the bullpup. Not that I'm going to patent or sell any of this, or that it would be illegal to share them, I'm just not sure I'm ready to dip my toe in the murky waters of "distributing firearm blueprints over the internet".

Oh, I wasn't talking about the files, I was meaning the printer settings like the filament, layer height, infill type and percentage, that kind of stuff. I've been working on a design for an AR handguard that's on hold until I have an AR to put it on and I'm curious what sort of gotchas you've found making accessories. The handguard seems like it would be a higher-stress area than most of the parts you've been doing due to its nature as a class 2 lever though, so I can see why ABS would do fine.

The solenoid design is extremely interesting, I didn't realize that the ATF had done an about-face on that, the last I heard they didn't like it because it was considered to be too easily converted, but maybe that's only for designs that aren't including mechanical parts including a disconnector.

I really do wonder if there could be some way to capture some of the energy from the bolt cycling , I wonder if the BCG material would be suitable for a linear generator using fixed magnets and windings? That would be a huge redesign of an already finicky system, just wondering about a way to make the system closer to self-sustaining. I like the design as far as getting rid of the trigger as a weak point in the bullpup design, I just don't like a gun that you have to recharge.

Makes sense that the gun is decently heavy, 7.3 pounds for the gun sans scope still includes the battery, and that lipo is still going to be a good ~4oz if it's anything like the 11.1v lipos I used to have for airsoft guns. And the BRN-180 has a government profile barrel IIRC, and a piston upper so you've got more mass than a DI design.

Friar Zucchini
Aug 6, 2010



I follow some poo poo on Facebook that posts photoshopped fake bullpup guns... or de-pupped AUG's, or whatever... but...

this is real. and it is BEAUTIFUL.

And what ever happened to people thinking that an electronic trigger was a machine gun because lol atf?

Target Practice
Aug 20, 2004

Shit.

Spitballing, but it seems like you could probably use the bolt cycling to move a magnet through a coil to generate some residual charge.

Maybe even like run the actual trigger system from a large capacitor that is only charged by the battery when it reaches some lower threshold. Otherwise the reciprocating bolt charge system would directly feed the capacitor so you wouldn't need complicated(?) battery recharging circuitry.

ThinkFear
Sep 14, 2007



Build a pump into the front handguard to charge it.

Serious question: Is there a noticeable delay / lock time with the solenoid trigger setup?

Brackit
Jan 23, 2019


ThinkFear posted:

Serious question: Is there a noticeable delay / lock time with the solenoid trigger setup?
In practice, no. I only noticed it when I was bench testing it and slapping the trigger with a pencil.

RE: optics mounting. What's on there now is certainly "good enough". The handguard, while technically removable, is still very rigid, and I definitely want a metal-on-metal path between the barrel and scope. If the handguard starts to become noticeably wobbly, I'll try making it more permanently attached. I mean, It's a piston gun, how often do you need to clean it, really?

Shima Honnou
Dec 1, 2010

The Once And Future King Of Dicetroit



College Slice

Friar Zucchini posted:

I follow some poo poo on Facebook that posts photoshopped fake bullpup guns... or de-pupped AUG's, or whatever... but...

this is real. and it is BEAUTIFUL.

And what ever happened to people thinking that an electronic trigger was a machine gun because lol atf?

wtf can you post a depupped aug for me real quick

Doctor Grape Ape
Aug 26, 2005

Dammit Doc, I just bought this for you 3 months ago. Try and keep it around for a bit longer this time.


ThinkFear posted:

Build a pump into the front handguard to charge it.

https://www.youtube.com/watch?v=9tNJeS6O6ds

Shaocaholica
Oct 29, 2002

Fig. 5E



Minority report was better

Kesper North
Nov 3, 2011

EMERGENCY POWER TO PARTY

This was already amazing, but

quote:

The attached lower has a standard, mil-spec trigger group, which is operated using an electronic solenoid.

made my eyes bug out.

infrared35
Jan 12, 2005

border patrol qt


Plaster Town Cop

Yeah, this is awesome.

DkHelmet
Jul 10, 2001

I pity the foal...


Having shot it, it is pretty awesome.

Gargamel Gibson
Apr 24, 2014



You've just rented a jet-ski to the Punisher.

KISS THAT BABY GOODBYE!

MrBusiness
Jan 19, 2016


You did it, you beautiful bastard. Can you uhh make a solenoid trigger for the MDR?

Shaocaholica
Oct 29, 2002

Fig. 5E


If electric triggers are legal, why arenít there any commercial ones? Too soon?

Pursesnatcher
Oct 23, 2016



Grimey Drawer

Shaocaholica posted:

If electric triggers are legal, why aren't there any commercial ones? Too soon?

There are, they're just primarily found in wannabe-olympics guns like the Walther E-SSP.

Kesper North
Nov 3, 2011

EMERGENCY POWER TO PARTY

Shaocaholica posted:

If electric triggers are legal, why arenít there any commercial ones? Too soon?

They don't hold up under the InRange MudTest.

Target Practice
Aug 20, 2004

Shit.

Remington had one at some point. Etronx?

22 Eargesplitten
Oct 10, 2010

Certified Centrist Trash


Shaocaholica posted:

If electric triggers are legal, why arenít there any commercial ones? Too soon?

I know for a while there were ATF concerns, they ruled some of them to be too easily converted to FA in the '90s from what I remember. I guess since this one still has a mechanical disconnector that the gun won't function correctly without, it's okay?

Doctor Grape Ape
Aug 26, 2005

Dammit Doc, I just bought this for you 3 months ago. Try and keep it around for a bit longer this time.


22 Eargesplitten posted:

I know for a while there were ATF concerns, they ruled some of them to be too easily converted to FA in the '90s from what I remember. I guess since this one still has a mechanical disconnector that the gun won't function correctly without, it's okay?

This is what I'm assuming but I'd love to know more/where the lines are.

Brackit
Jan 23, 2019


Nobody would buy a gun that stops working when the the battery dies.

FWIW, this is hardly the easiest way to make an AR full-auto. Some guy did it with a bent coat hanger. Unless the ATF has changed their position since 2013, this system should be fine, since I never intend to make it full-auto, and as designed, it is not "easily" convertible to full-auto without adding a bunch of extra circuitry.

I heard the MDR had a pretty good trigger?

wheres my beer
Apr 29, 2004


Tryin' to catch me ridin' dirty


Fun Shoe

The MDR I handled had an acceptable trigger.

Shaocaholica
Oct 29, 2002

Fig. 5E


Brackit posted:

Nobody would buy a gun that stops working when the the battery dies.

Competition shooters would. They shoot guns so tweaked that if youíre not shooting just the right hand load it fails to feed

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Kafouille
Nov 5, 2004

Think Fast !

You could make a gun that has a conventional trigger but some free travel that closes an electrical contact first, so you'd fire electric if that works but still have the gun work if that dies.

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