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  #1  
Old 07-12-2009, 06:22 AM
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Bullpup Stock Design Update



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I have finished my CAD design for the BulZi Bullpup 1.0. While the design may still change a bit after the first few builds, I am pretty sure that this one will perform very well and be easy to build.

This is a Bullpup stock design unlike any other available for the Ruger (and possibly anything else either). It is designed to be flexible and adjustable with a large adjustment range for length of pull, easily customizable wooden cheekpiece, grip and forestock, and the ability to accept AR-15 style pistol grips. The baseline ergonomics are based on the Walther WA-2000 but the rifle is not meant as a cosmetic clone.

It can be manufactured by anyone with access to a 3-axis milling machine. CNC is very helpful but not absolutely necessary. Material removal is kept to a minimum, so it is within the range of small desktop mills. There are 15 machined parts. Simple fixturing is anticipated, with fixture features incorporated into the part designs.

All materials are low-cost and readily available. The action internals (hammer, sear, disconnector, ejector, bolt stop, springs, pins) are taken from Ruger factory assemblies, which can be purchased or salvaged from ultimate build scraps.

The most innovative aspect, however, is the trigger and action design. The mechanical trigger operates an electrical switch, which fires a solenoid incorporated into the rear action. Thus, the trigger haptics are completely separate from the hammer-sear-mainspring interaction. The trigger pull should rival the best mechanical designs, which is unheard of for a bullpup. The spring plunger used in the design is the same as those used in Kidd triggers. A trigger adjustable down to 10's of grams of pull easily actuates an 8lb action. The trigger is adjustable for pretravel and there is no need for post travel. A two-stage feel can be accomplished by screwing in another spring plunger.

Due to the design of the circuit, electronic doubles and automatic fire are not possible. The maximum rate of fire is 1 round per second, set by the capacitor charging time.

As far as legality, this design is no different from several semiautomatic .22LR olympic pistols that use a solenoid to release the sear. These pistols are sold in the US with no BATFE problems.

If anyone wants the CAD and more details on construction, PM me.



Last edited by BulZi; 07-12-2009 at 10:42 AM.
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Old 07-12-2009, 09:42 AM
Mohave-Tec

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Acad

If you know how to use drafting software, you probably know how to fit pixels to a page. I have a 22 inch wide screen monitor and can only see half the drawing.
Nice picture tho, best I can tell.
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Old 07-12-2009, 05:08 PM
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I like the front end, but the shape and angle of the pistol grip doesn't excite me. I like
the idea of the solenoid fired electronic trigger.
John
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Old 07-12-2009, 07:24 PM
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It is clever. Much thought went into this. I wish I could see more of the triggering configuration. I can see the overall drawing better. LOL.
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Old 07-13-2009, 11:56 PM
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pistol grip is standard AR-15 mount compatible

The pistol grip is definitely one of the things people like to customize.

To achieve maximum flexibility, I made the mount for the pistol grip compatible with the dimensions from an AR-15. The AR has many aftermarket pistol grips available with different angles and materials.

The ability to use wood is also nice, since anyone with a dremel or even a pocket knife and sandpaper could make one from scratch or purchase a rough blank and go to work on it.

Here is a picture with the AR grip on it.

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Old 07-14-2009, 12:13 AM
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trigger group diagram

Here is a quick view of the trigger group. It is almost identical in layout to the factory group and uses factory parts such as the sear, hammer, ejector, bolt stop, springs, and pins.

I have used the parts that you get with a complete plastic trigger group for ~$50 from Brownells. The plastic parts are of no concern because NONE of them are used, the only thing plastic on this gun is the tuffer buffer and a piece of electrical insulation in the switch.

At any rate, the action frame is made from pieces of aluminum that bolt together. This allows them to be machined from standard Aluminum bar stock very quickly and cheaply. The surfaces can also be polished flat and complete disassembly and reassembly is easy for cleaning.

The trigger bar is machined from a standard .5" U-channel of aluminum, again, in order to make CNC machining quick and easy. The bar extends back below and behind where the factory trigger would be. The bar is pulled upward by the solenoid plunger when the circuit is fired, and then it is returned by a spring that fits into a recess just forward of the solenoid. The disconnector works just like the factory design.

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Old 07-14-2009, 10:04 AM
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B-E-A-utiful work! pm sent.
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Old 07-14-2009, 04:54 PM
saikatana
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Bullpup Stock Design

That is a wonderful design, simple yet addressing many issues not the least of which is how to make the trigger work without a linkage. Could the selonid be housed in the grip on a more conventional looking rifle and still activate the trigger?? Thinking of Smallbore Silhouette where centerline of the bore is upper limit of comb.
Great design and drawing.
Saikatana
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Old 07-14-2009, 05:22 PM
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Low mount solenoid for conventional non-bullpup

The solenoid action can definitely be adapted to a more conventional stock layout. It can sit where the mag release lever (loop lever) is currently depicted. The mag release lever then needs to be reshaped a bit and extended down below the solenoid housing.

I don't know whether someone would go to the trouble of a solenoid trigger for a non-bullpup. It was my understanding that there were already pretty good triggers available (Kidd, Jard, etc.) albeit for a price, that would be fully compatible with all aftermarket stocks.

If you would like to see that configuration just let me know.
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Old 07-14-2009, 05:36 PM
saikatana
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Bullpup Stock Design Update

I would love to see such a conventional layout for the 10/22 Ruger using you trigger.. The barrel threaded to the action, a Power Custom scope mount attached to barrel and action, and your trigger would make a winning combination I think. Also most people don't realize that the last 2 fingers give most of the grip strength to your hand, but that is where few grips are smaller to allow this action. I think this is another area where the weapon can be made to fit the shooter.
Thanks
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Old 07-14-2009, 06:20 PM
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hay, can you make your pics a lot bigger?

wanna test out my new 24" flat screen and now i only have to scroll
over 1/2 way,

thanks, Rico....








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  #12  
Old 07-14-2009, 10:53 PM
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Pixel Problems

To all with "too many pixels" type problems, assuming that you have a newer browser, you can zoom any web page in or out simply by holding the Control key and scrolling the mouse wheel.

I work on a big monitor, and don't believe in downsampling everything. You can always downsample yourself with a click and a mouse, but small pictures look bad when you zoom in on them.

If that is too complicated, fine, but I am not sure you should be operating firearms.
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Old 07-16-2009, 03:25 AM
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You need to check the legality of the electric solenoid. I recall them making an opionion that electronically activated triggers on a semi was illegal.

They stated that by using a electronicically actuated hammer it made it too easy for someone to install a circuit to allow full auto fire.

I like the design and looks of it, if it would prove to be accurate I would probably buy one.

Gordon
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Old 07-16-2009, 07:47 AM
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Legality of solenoid sear tripper

I have checked the legality of using a solenoid in the trigger mechanism to achieve 1-shot per 1-pull in a semiautomatic weapon and it is perfectly legal. You can order the Pardini SP1-Electronic today if you don't believe me.

http://www.pardini.it/weapon/target_pistols-sp1-sp1.htm

Quoting an earlier thread I started:

---

Several times in the past, people have proposed making a nice tunable trigger which is actually an electronic switch, which then triggers a solenoid to disengage the sear and fire the weapon. For a bullpup stock, this has the advantage of removing the need for a sloppy mushy linkage.

Many people have stated on this forum that an electronic switch triggered solenoid which disengages the sear and causes firing (one shot per trigger pull) is somehow illegal when used in a semiautomatic weapon because it would be "too easy" to make it fully automatic and therefore the weapon would be considered "readily restorable" to be a machine gun by the BATFE.

There is at least one major manufacturer with a semiautomatic pistol sold legally in the USA right now that use this exact system. I have written to the US dealers of this pistol and they say that there has never been any problems from an ATF standpoint with their weapons ( http://www.pardini.it/weapon/target_pistols-sp1-sp1.htm ).

In this diagram ( http://www.pardini.it/manuali/sp1%20elettronica.pdf ) the sear is labeled 738-E and the solenoid assembly is 760. Some of the product documentation shows a better view of this arrangement. The SP1 has a 5-round clip, and is clearly semiautomatic. It is not just an electronic one-shot free pistol like those of Haemmerli and Morini.

With this pistol on the market, I don't see how BATFE could argue with a solenoid tripped semiautomatic 10-22, so long as it was one pull one shot.

There are two more semi-auto's with electronic triggers, designed by Morini's new company Match Guns. http://www.matchguns.com/schedaprodotto.asp?prod_id=12

---

I have spoken and corresponded with the US sales reps for the Pardinis. They are absolutely legal, and there has never been any issue with BATFE.

As to the notion that these are "too easy" to make full auto, it is true that a "simple modification" to the circuit (for someone with electronics knowledge and access to decent facilities) would enable FA fire, but this modification would not be "readily" performed - IE, not with the flip of a switch. If someone did design and install a switchable FA capability or any other FA option, they would be breaking the law.

The point is, the firearm as I have designed it takes way more time, effort, knowledge, tools, and parts to "readily restore" it to FA than a bone-stock Walmart 10-22, which can be made FA using a bench grinder, or even sandpaper or the sidewalk. So by the standard of "readily restorable" interpreted as "easy to make FA given limited knowledge, time, and tools" then all 10-22's are illegal machine guns.

"Readily restorable" means more than just "easy to make FA given limited knowledge, time, and tools."

And if you don't actually modify to achieve more than 1-fire to 1-pull, it will never become an issue.

The circuit I have designed has a fixed time required to recharge the capacitor, and doesn't begin charging until you let off the trigger, so it is guaranteed to be 1-fire 1-pull with very high reliability.

Last edited by BulZi; 07-20-2009 at 06:57 PM.
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  #15  
Old 07-20-2009, 07:05 PM
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with top rail, rendered in black

Here is a slight design update - The top rail now extends as far as the bottom rail, in order to provide more real estate up top for forward mounted sights and peripherals, and to add even more rigidity to the design.

Also, I have added an ATI aftermarket rubber buttpad which is shown. This thing costs about $14 and adds 1/2 inch LOP. The LOP of my stock is adjustable over a range of a few inches by loosening two bolts on the trigger frame and sliding back along a slot in the lower rail.

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